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Mettler Toledo ME403E Precision Balance – Used & Refurbished
The Mettler Toledo ME403E Precision Balance is a compact high-resolution laboratory balance combining 420 g maximum capacity with 1 mg / 0.001 g readability. Designed for routine quantitative weighing, sample preparation, formulation, quality control, and research applications, the ME403E provides substantially finer resolution than conventional 0.01 g precision balances while maintaining a practical 420 g working capacity.
Available used and refurbished from American Instrument Exchange, the Mettler Toledo ME403E features a fully enclosed draft shield, 120 mm stainless steel weighing pan, backlit LCD display, external adjustment, RS232 connectivity, robust die-cast aluminum construction, and multiple integrated weighing applications.
Its straightforward controls and external calibration system make the ME403E particularly attractive for laboratories that want high-resolution weighing performance without the complexity of a premium analytical-balance platform.
Each balance is inspected, cleaned, calibrated, and tested for weighing performance before shipment and includes a 90-day warranty from American Instrument Exchange.
Key Features
420 g maximum weighing capacity
1 mg / 0.001 g readability
Repeatability limit of 1 mg
Typical repeatability of approximately 0.7 mg
Linearity deviation limit of 2 mg
Typical linearity deviation of approximately 0.6 mg
Typical USP minimum sample weight of approximately 1.4 g
Typical minimum weight of approximately 140 mg at 1% tolerance
Approximately 1.5-second settling time
External adjustment
120 mm diameter stainless steel weighing pan
Fully enclosed draft shield
Approximately 173 mm usable draft-shield height
Backlit LCD display
Integrated RS232 interface
Multiple built-in weighing applications
Front-mounted level bubble
Two adjustable leveling feet
Die-cast aluminum and ABS housing
Used, refurbished, calibrated, and tested by American Instrument Exchange
90-day warranty included
Overview
The Mettler Toledo ME403E occupies a useful position between conventional precision balances and higher-sensitivity analytical balances.
With 1 mg readability and 420 g capacity, it provides ten times finer displayed resolution than a 0.01 g precision balance while offering considerably more capacity than many traditional analytical balances.
This combination makes the ME403E particularly useful for laboratories whose applications require milligram-level measurement but do not necessarily require 0.1 mg analytical-balance resolution.
The 420 g capacity also provides useful headroom for weighing containers, vessels, filters, and other tare items in addition to the sample itself.
Mettler Toledo designed the ME series around straightforward routine operation. A bright backlit display, simple controls, easily accessible leveling system, RS232 connectivity, and built-in weighing applications allow technicians to perform common procedures without navigating a complicated user interface.
For laboratories prioritizing reliable milligram-level weighing and ease of operation, the ME403E offers a practical solution.
Common Applications
The Mettler Toledo ME403E is well suited for sample preparation, reagent weighing, formulation, chemical preparation, quality control, research, ingredient weighing, filter weighing, percentage weighing, density determination, check weighing, totaling, and other routine quantitative laboratory procedures.
Pharmaceutical and biotechnology laboratories can use the ME403E for reagent preparation, research samples, formulation ingredients, media components, and routine laboratory measurements.
Chemical laboratories can use the balance for compound preparation, solution preparation, research, and general quantitative weighing.
Food and beverage, cosmetics, environmental, materials science, industrial, academic, and quality-control laboratories can use the ME403E when milligram-level resolution is required but a 0.1 mg analytical balance would provide more sensitivity than the procedure requires.
Ideal Laboratory Types
The ME403E is a strong choice for pharmaceutical, biotechnology, chemical, environmental, food and beverage, cosmetics, materials science, academic, industrial research, and quality-control laboratories.
It is particularly useful as a general-purpose high-resolution balance in laboratories that perform a wide variety of sample-preparation procedures.
Its 1 mg readability provides considerably finer resolution than typical 0.01 g or 0.1 g toploading balances.
At the same time, its 420 g capacity gives technicians enough working range for containers and samples that might exceed the capacity of smaller analytical balances.
This combination can make the ME403E an excellent primary balance for routine quantitative work or a useful complement to a more sensitive analytical or semi-microbalance.
Milligram-Level Precision Weighing Performance
The Mettler Toledo ME403E provides 1 mg / 0.001 g readability throughout its 420 g weighing range.
Mettler Toledo specifies a repeatability limit of 1 mg, with typical repeatability of approximately 0.7 mg under appropriate operating conditions.
The manufacturer specifies a linearity deviation limit of 2 mg, with typical linearity deviation of approximately 0.6 mg.
This level of performance allows the ME403E to reliably resolve relatively small mass differences while maintaining enough capacity for routine sample preparation and formulation work.
For laboratories whose procedures require milligram-level measurement rather than sub-milligram analytical resolution, the ME403E provides an attractive balance between sensitivity, capacity, and ease of use.
Minimum Sample Weight & USP Applications
Mettler Toledo specifies a typical USP minimum sample weight of approximately 1.4 g for the ME403E under stated reference conditions.
The manufacturer also specifies a typical minimum weight of approximately 140 mg at a 1% tolerance.
These figures illustrate an important principle in laboratory weighing: readability does not equal minimum sample weight.
Although the ME403E displays measurements in 1 mg increments, quantitative weighing requires a sufficiently large sample to maintain the measurement uncertainty permitted by the procedure.
Actual minimum weight depends on repeatability, calibration status, installation quality, environmental conditions, and the performance of the individual balance.
For USP, GMP, GLP, or other controlled applications, laboratories should establish minimum sample weight according to the installed balance and the uncertainty requirements of the weighing procedure.
Controlling Drafts, Vibration & Static
At 1 mg readability, environmental influences can affect weighing results.
Air movement, vibration, temperature changes, static electricity, unstable work surfaces, and incorrect leveling can all increase measurement variation.
The ME403E incorporates a fully enclosed draft shield that helps protect the weighing pan and sample from routine laboratory airflow.
The balance should still be installed on a rigid, stable, level work surface away from significant vibration sources such as centrifuges, shakers, pumps, and compressors.
Static electricity can also become relevant when weighing powders, filters, plastic containers, and other materials that readily accumulate charge.
Proper installation and good weighing technique help the ME403E achieve its intended milligram-level performance.
External Calibration & Adjustment
One of the most important distinctions of the ME403E is its external adjustment system.
The ME403E does not incorporate an automatic internal calibration weight.
Instead, adjustment is performed using an appropriate external reference weight.
This distinguishes the ME403E from the closely related ME403, which incorporates internal adjustment.
External adjustment provides a straightforward and cost-effective approach for laboratories that already maintain certified calibration weights or operate under procedures requiring routine external verification.
For quality-controlled applications, laboratories should use calibration weights of the appropriate class and establish adjustment and verification intervals according to their internal procedures.
American Instrument Exchange calibrates and evaluates each refurbished ME403E before shipment using appropriate reference weights.
Draft Shield & 120 mm Weighing Pan
The ME403E incorporates a 120 mm diameter stainless steel weighing pan enclosed within a draft shield.
The draft shield provides approximately 173 mm of usable interior height, giving technicians room for many common weighing vessels, sample containers, filters, weighing papers, and laboratory accessories.
The enclosure reduces the influence of air movement on the weighing cell, which becomes increasingly important at 1 mg readability.
Glass panels also allow users to observe the sample clearly while protecting the weighing area from surrounding laboratory activity.
The stainless steel pan provides a durable, easy-to-clean weighing surface suitable for routine laboratory use.
Straightforward Operation & Easy Leveling
The ME403E was designed around straightforward routine operation rather than a complex touchscreen interface.
A backlit LCD display with large characters makes weighing results easy to read under typical laboratory lighting conditions.
The balance also uses two large adjustable leveling feet rather than four smaller feet.
A conveniently positioned level bubble allows technicians to verify proper leveling before beginning quantitative work.
These seemingly simple design features can be valuable in busy multi-user laboratories where balances must be easy to operate correctly without extensive training.
Built-In Applications
The ME403E provides multiple integrated applications that extend its functionality beyond straightforward mass determination.
Available functions include applications for tasks such as density determination, check weighing, totaling, formulation, percentage weighing, piece counting, and other routine weighing procedures.
Built-in applications can reduce manual calculations and simplify repetitive laboratory work.
For laboratories that do not require advanced method-management software, the ME403E provides useful application functionality without adding unnecessary complexity to routine operation.
RS232 Connectivity & Documentation
The ME403E incorporates an RS232 interface for connection to compatible laboratory peripherals.
Weighing results can be transferred electronically to compatible printers or computer systems rather than manually transcribed.
This can improve workflow efficiency and reduce the potential for transcription errors.
For routine quality-control and research environments, direct data transfer provides a straightforward way to create weighing records without requiring the more elaborate data-management infrastructure found on premium balance platforms.
Key Specifications
Specification
Mettler Toledo ME403E
Balance Type
High-Resolution Precision Balance
Maximum Capacity
420 g
Readability
1 mg / 0.001 g
Repeatability Limit
1 mg
Typical Repeatability
Approx. 0.7 mg
Linearity Deviation Limit
2 mg
Typical Linearity Deviation
Approx. 0.6 mg
Typical USP Minimum Weight
Approx. 1.4 g
Typical Minimum Weight at 1% Tolerance
Approx. 140 mg
Settling Time
Approx. 1.5 seconds
Adjustment
External
Weighing Pan
120 mm diameter
Draft Shield
Enclosed
Usable Draft-Shield Height
Approx. 173 mm
Overall Dimensions
210 mm W × 319 mm D × 289 mm H
Balance Weight
Approx. 4.4 kg
Display
Backlit LCD
Interface
RS232
Housing
Die-cast aluminum / ABS
Legal for Trade
No
Choosing Between a 1 mg Precision Balance and a 0.1 mg Analytical Balance
The ME403E provides 1 mg readability, placing it between conventional precision balances and analytical balances in terms of resolution.
A standard analytical balance typically provides 0.1 mg readability, making it ten times more sensitive than the ME403E.
That additional resolution is valuable for standards preparation, quantitative analytical chemistry, gravimetric analysis, and procedures involving smaller sample quantities.
However, greater sensitivity also increases susceptibility to airflow, vibration, static, and temperature variation.
For routine reagent weighing, sample preparation, formulation, quality control, and other procedures where 1 mg resolution is sufficient, the ME403E can be easier and faster to operate.
The correct choice should therefore be based on the smallest quantity the laboratory needs to measure reliably—not simply on purchasing the balance with the greatest number of displayed decimal places.
ME403E vs. ME403
The ME403E and ME403 both provide 420 g capacity and 1 mg readability.
The principal difference is the adjustment system.
The ME403E uses external adjustment, requiring an appropriate external reference weight when adjustment is performed.
The ME403 incorporates internal adjustment, allowing the balance to adjust itself using a built-in reference weight.
The ME403 may therefore be preferable in laboratories where convenience and frequent automatic adjustment are priorities.
The ME403E is an excellent alternative for laboratories that already maintain appropriate external calibration weights or prefer external adjustment as part of their established calibration procedures.
This distinction is important when purchasing either model because the E suffix identifies the externally adjusted configuration.
ME403E vs. 0.01 g Precision Balances
A conventional 0.01 g precision balance displays measurements in 10 mg increments.
The ME403E displays measurements in 1 mg increments, providing ten times finer resolution.
That additional resolution can be valuable for smaller reagent quantities, formulation ingredients, research samples, and quality-control procedures.
The tradeoff is generally capacity and environmental sensitivity.
Many 0.01 g precision balances provide capacities ranging from several kilograms to more than 10 kg, while the ME403E has a maximum capacity of 420 g.
The ME403E is therefore best suited for laboratories prioritizing smaller samples and finer measurement resolution, while higher-capacity 0.01 g balances are better suited for larger vessels and kilogram-scale preparation.
Refurbishment & Performance Testing
Every used Mettler Toledo ME403E sold by American Instrument Exchange is inspected, cleaned, refurbished as necessary, calibrated, and tested before shipment.
Our technicians use appropriate calibration weights to evaluate critical performance characteristics including accuracy, repeatability, linearity, corner-load tolerances, stability, and reduced span across appropriate portions of the weighing range.
Because the ME403E uses external adjustment, its weighing performance is calibrated and verified using appropriate external reference weights.
The weighing cell, display, controls, draft shield, leveling components, weighing pan, RS232 interface, and other installed functions are inspected and tested for proper operation.
The weighing chamber and pan are thoroughly cleaned, and the balance receives a final operational inspection before shipment.
Each refurbished ME403E includes a 90-day warranty from American Instrument Exchange.
Shipping & Installation Considerations
American Instrument Exchange securely prepares the ME403E for shipment to protect its weighing cell, stainless steel pan, draft-shield glass, display, and electronic components.
Once received, the balance should be installed on a rigid, stable, level laboratory work surface away from strong airflow and significant vibration.
The instrument should be allowed to acclimate to the laboratory environment before final adjustment, calibration verification, and critical quantitative measurements are performed.
Because the ME403E uses external adjustment, laboratories planning to perform adjustment or routine performance checks should maintain appropriate reference weights for the required procedures.
For regulated applications, installation should be followed by appropriate calibration, verification, minimum-weight determination, or qualification according to the laboratory's quality system.
Related Laboratory Equipment
American Instrument Exchange maintains an extensive inventory of used and refurbished laboratory balances, including analytical balances, semi-micro balances, microbalances, and precision balances for applications ranging from routine sample preparation to high-resolution quantitative analysis.
What is the maximum capacity of the Mettler Toledo ME403E?
The ME403E has a maximum weighing capacity of 420 g.
What is the readability of the ME403E?
The ME403E provides 1 mg, or 0.001 g, readability throughout its weighing range.
Is the ME403E an analytical balance?
The ME403E is best classified as a high-resolution precision balance. Its 1 mg readability is finer than most general-purpose precision balances but less sensitive than a conventional analytical balance, which typically provides 0.1 mg readability.
What is the typical repeatability of the ME403E?
Mettler Toledo specifies typical repeatability of approximately 0.7 mg, with a repeatability limit of 1 mg.
What is the typical USP minimum weight of the ME403E?
Mettler Toledo specifies a typical USP minimum weight of approximately 1.4 g under reference conditions. Actual minimum weight should be determined according to the performance of the installed balance and the laboratory's uncertainty requirements.
Does the ME403E have internal calibration?
No. The ME403E uses external adjustment. Appropriate external reference weights are required when adjustment is performed.
What is the difference between the ME403E and ME403?
Both models provide 420 g capacity and 1 mg readability. The ME403E uses external adjustment, while the ME403 incorporates internal adjustment.
Does the ME403E have a draft shield?
Yes. The ME403E has an enclosed draft shield with approximately 173 mm of usable interior height, helping protect milligram-level measurements from laboratory air movement.
Can the ME403E send weighing results to a printer or computer?
Yes. The ME403E incorporates RS232 connectivity for electronic transfer of weighing results to compatible devices.
Is the ME403E Legal for Trade?
No. The standard ME403E is not a Legal-for-Trade approved balance.
Why purchase a refurbished Mettler Toledo ME403E?
A refurbished ME403E provides laboratories with 420 g capacity, 1 mg readability, an enclosed draft shield, straightforward operation, external adjustment, built-in weighing applications, and RS232 connectivity at a lower acquisition cost than comparable new laboratory balances. American Instrument Exchange tests, calibrates, cleans, and refurbishes each balance before shipment and provides a 90-day warranty.
CLICK HERE to see the Mettler Toledo ME403E analytical balance on our YouTube channel
Testing Procedures for Used and Refurbished Laboratory Balances
Ensure Precision, Repeatability, and Weighing Accuracy
Used and refurbished laboratory balances from American Instrument Exchange undergo thorough, multi-point testing to ensure accurate, reliable performance in scientific, industrial, and pharmaceutical settings. Each balance is carefully inspected, calibrated, and evaluated to meet the stringent standards required for analytical, precision, and micro weighing applications.
Why Testing Used Laboratory Balances Is Essential
Before a laboratory balance is placed back into service, it must be rigorously tested for:
• Weighing accuracy across full capacity range
• Repeatability and linearity
• Load cell and sensor functionality
• User interface and calibration system integrity
Comprehensive balance testing helps eliminate measurement errors and guarantees performance in high-precision environments such as R&D, formulation labs, and quality control facilities.
Our structured balance testing protocol ensures every refurbished unit delivers consistent results and trusted performance.
Key Testing Procedures for Refurbished and Used Laboratory Balances
1. Initial Visual Inspection
• Inspect housing, leveling feet, draft shield, and weighing pan for wear, cracks, or corrosion
• Check control panel, power cord, and buttons for damage or signs of tampering
• Confirm presence and condition of all required components (e.g., shields, adapters, trays)
2. Functional Startup and Interface Testing
• Power on the balance to verify display initialization and zeroing functionality
• Test user interface responsiveness, menu access, and programmable features
• Evaluate stabilization time and auto-tare functions
3. Calibration and Accuracy Testing
• Perform internal calibration (if equipped) and verify operation
• Use certified calibration weights to perform external calibration
• Check for accuracy at multiple weight points across the balance’s range
4. Repeatability, Linearity, and Corner Load Testing
• Conduct multiple weighings of identical test weights to confirm repeatability
• Test linearity by weighing at low, mid, and high points across the range
• Evaluate corner-load accuracy by placing test weights at different positions on the pan
5. Load Cell and Sensor Integrity Verification
• Test load cell response for consistency, drift, or hysteresis
• Verify sensor functionality and precision at sub-milligram levels (for analytical/microbalances)
6. Electrical Safety and Grounding Checks
• Inspect wiring and power components for safety and compliance
• Verify proper grounding and electrical insulation to meet lab equipment standards
7. Final Quality Assurance and Documentation
• Perform a full operational test under simulated lab conditions
• Record and document all calibration results and test metrics
• Final cleaning and inspection before shipping
Trusted Performance from American Instrument Exchange
All refurbished laboratory balances from American Instrument Exchange are tested and validated to deliver precision weighing performance from day one. Our expert technicians use industry-standard procedures to ensure each balance is lab-ready—whether used for sample prep, formulation, or high-precision research.
Repair and Refurbishment Protocol for Used Laboratory Balances
Precision Weighing Restored by American Instrument Exchange
At American Instrument Exchange, every used laboratory balance is subjected to a multi-step refurbishment protocol designed to restore precision and reliability with laboratory standards. Whether it’s an analytical balance, precision balance, or microbalance, we ensure each unit delivers consistent performance for scientific, pharmaceutical, and industrial applications.
Why Choose a Refurbished Laboratory Balance from American Instrument Exchange?
• Fully tested for accuracy, repeatability, and calibration stability
• Backed by a warranty
• Cost-effective alternative to purchasing new balances
• Environmentally responsible through expert refurbishment and reuse
• Refurbished by technicians with extensive experience in lab instrumentation
Every laboratory balance from American Instrument Exchange is professionally restored through a comprehensive, multi-point process:
1. Initial Intake & Inspection
• Exterior inspection for damage, corrosion, and wear on display, housing, and leveling feet
• Visual/manual check of weighing pan, draft shield, doors, and buttons
• Documentation of missing parts, error codes, or component issues
2. Cleaning and Decontamination
• Thorough cleaning of the weighing chamber, pan, and internal components using anti-static and non-abrasive cleaners
• Removal of dust, chemical residue, and particulate buildup
• Disinfection of all surfaces
3. Mechanical and Electronic Repairs
• Replacement/repair of worn components including pans, draft shields, and buttons
• Evaluation and repair of load cells, sensors, and electronic boards
• Inspection of power supply, internal wiring, and display screen functionality
4. Calibration and Accuracy Testing
• Internal calibration mechanisms are tested (if equipped)
• External calibration is performed using certified traceable weights
• Repeatability, linearity, and corner-load accuracy are verified
5. Functional Testing and Performance Validation
• Test of user interface, menu settings, and programmable functions
• Taring, zeroing, and stability response times are evaluated
• Load-bearing accuracy is tested across the unit’s full capacity range
6. Compliance and Safety Checks
• Electrical system testing for grounding and safe operation
• Verification of leveling system and anti-vibration performance
7. Final Quality Control and Documentation
• Final inspection and multi-point accuracy verification
• Complete operational test with weight logs and calibration reports
• Full cleaning and packaging for shipment
Trust the Experts at American Instrument Exchange
With over 50 years of experience in laboratory equipment, American Instrument Exchange is a trusted source for precision-refurbished laboratory balances. Our refurbishment protocol ensures each balance meets strict standards for accuracy and performance—ready to deliver dependable weighing results from day one.
Warranty Information
All used equipment sold by American Instrument Exchange is refurbished/reconditioned, tested to meet specifications, cleaned, and comes with a 90-day warranty from the date of shipment unless otherwise specified. New products include a warranty from the manufacturer. Your warranty is only valid if you have paid your invoice. If your invoice is over 30 days old, warranty work will not be performed until your invoice is paid in full. American Instrument Exchange is not liable for any special or consequential damages that result from the use of, or the inability to use, the materials on this site or the performance of the products,
Exceptions include international sales and items that are agreed to be sold with a lesser warranty or items that are agreed to be sold “as is.”
Should there be visible shipping damage to packaging or concealed shipping damage to item(s) supplied, buyer must communicate such damage to the delivering entity or carrier upon receipt first and to American Instrument the same day item is accepted / signed for. Failure to do so voids warranty. Customer decision to involve / procure third party or OEM service other than American Instrument or AIE assigned vendors to resolve in-warranty instrument failure or defect without first placing a service call to American Instrument voids warranty.
Return & Cancellation Policy
American Instrument Exchange will authorize the return of and issue a full refund for any equipment that is not working as represented and could not be replaced or repaired to the customer’s satisfaction by AIE or a representative of AIE during the warranty period. Returns without prior authorization and an RMA number will not be accepted.
Customers are responsible for proper packaging of the equipment and all included accessories. American Instrument will pay for insurance and shipping costs. Non-inventory items bought specifically to fill customer orders may possibly be returned, but on a case by case basis.
Customers who cancel orders after refurbishing has begun or after delivery where there are no equipment performance issues may be subject to a Restocking/Cancellation Fee of 20% or more and responsible for shipping costs for both the delivery and return.
Ongoing and Extended Support Options
American Instrument Exchange is able to provide additional repair and support services outside the warranty terms for most products that sell.
For biosafety cabinets, clean benches, chemical fume hoods, and other clean air products our team at AIE Laboratory Services can provide certifications, repairs, decontaminations, and other services for customers throughout New England, and guidance and limited technical assistance for any customers in the US and Canada for new or refurbished biosafety cabinets purchased from American Instrument Exchange.
For all other products, the repair service team at American Instrument Exchange can provide both field and depot repair evaluations. We can easily schedule and coordinate the pick-up and transportation of your malfunctioning equipment. By offering hourly rates lower than most OEM service providers and eliminating travel time for technicians, we help reduce repair costs. Furthermore, our lab depot repair service minimizes or eliminates scheduling delays. Our experienced service technicians are qualified to restore your equipment to factory specifications.
Yes, all equipment from American Instrument Exchange comes with a warranty. Used/reconditioned/refurbished equipment is tested to make sure it operates to the manufacturer's specifications and comes with a 90-day warranty (unless otherwise noted). New equipment comes with a warranty from the manufacturer.
How do you test and recondition the equipment?
Testing requirements vary across all the equipment categories we sell. Temperature controlled units are tested with NIST traceable probes and data loggers. Gaskets, external housing, glass, handles, controls and control screens are all thoroughly inspected for integrity and functionality. We test all equipment using the manufacturer's parameters and specifications to confirm that the unit operates properly.
How do products ship from American Instrument Exchange?
We can ship products both nationally and internationally using a well-established network of transporters. Smaller items will ship via UPS. Larger equipment will be palletized and shipped either LTL or air-ride, depending on the specific equipment and/or delivery requirements.
Return and order cancellation policy
American Instrument Exchange will accept the return of any product that is not working as represented and could not be replaced or repaired to the customer's satisfaction during the warranty period. Customers who cancel orders after refurbishing has begun will be subject to a cancellation and restocking fee of between 20% and 40%.
Are discounts available for educational or non-profit institutions, or for bulk purchases?
Yes – call or email us today with a list of equipment you're looking for and we can potentially put together a quote that includes a discount.
How does your price matching policy work?
We strive to keep our pricing competitive and reasonable. If you find comparable items for sale at a lower price from other vendors please send us a link and or quote for the item and we'll do our best to match or beat the price.
Can I see the equipment in person before committing to a purchase?
Customers are welcome to make an appointment to view equipment in our warehouse. Given our workload we may not be able to test or clean the equipment prior to your arrival if you have not committed to an order.
1023 Western Avenue is a working warehouse, not a showroom, and customers should dress appropriately and wear closed toe shoes.
Can I ship products that I purchased elsewhere to American Instrument for repair?
Yes – please see our repair services page for more information.
