A&D EJ-123 120 g × 0.001 g Milligram Balance Guide
- pete8781
- Jul 31
- 4 min read
Need more details or help choosing the correct item? Call MNM Scales at (832) 290-3120 or email mnmscales@yahoo.com.
The A&D EJ-123 120 g × 0.001 g milligram balance is a compact precision instrument designed for users who need true 1 mg display resolution without moving to a much larger analytical-balance platform. Its combination of a 120 g capacity, anti-draft protection, stainless weighing pan, battery portability and advanced counting functions makes it useful in classrooms, small laboratories, jewelry work, formulation, hobby applications and controlled parts counting.
What the EJ-123 is designed to do
A&D positions the EJ series as compact precision balances, and the EJ-123 is the 120 g model with 0.001 g readability. A&D documents a 110 mm diameter weighing pan for the milligram EJ models, an anti-static breeze break for the EJ-123/303, adjustable response characteristics for drafts and vibration, and operation from either the supplied AC adapter or four AA batteries. MNM’s listing also specifies a backlit LCD, approximately 70 hours of alkaline-battery operation with the backlight off, and a factory calibration-weight setting of 100 g.
Key performance numbers
The published capacity is 120 g and the minimum displayed division is 0.001 g. MNM lists repeatability at 0.003 g and linearity at ±0.003 g. The display updates ten times per second. For percentage work, the listing gives a 0.01% minimum display and a 0.1 g minimum 100% reference weight. For counting, the model supports sample sizes of 5, 10, 25, 50 or 100 pieces, a 0.001 g minimum unit weight and a maximum displayed count of 120,000 pieces. Those numbers make the EJ-123 especially useful when the individual piece weight is small but still large enough to be resolved consistently by a 1 mg balance.
Breeze break and weighing environment
At 0.001 g readability, air movement matters. The EJ-123 includes the style of clear breeze break shown by A&D for the 1 mg models, helping reduce instability from room airflow and operator movement. Place the balance on a rigid, level surface away from HVAC discharge, open doors, vibration, direct sun and rapidly changing temperatures. Give the balance time to reach room conditions after moving it. If a reading wanders, environment and sample temperature should be checked before assuming the load cell or calibration has failed.
Counting, percentage and density functions
The EJ-123 is more than a simple gram display. Its ACAI counting function improves the stored unit-weight estimate as more pieces are added, which can reduce counting error when small components have slight mass variation. Percent mode is useful for formulation checks, coating pickup, comparative samples and classroom demonstrations. A&D also supports density determination on the EJ-123/303 with the optional EJ-13 density kit, making the model useful for education and basic material evaluation where a full analytical laboratory system is unnecessary.
Calibration and verification
The EJ-123 uses external-weight calibration rather than an internal motorized calibration mass. A&D’s manual instructs the user to warm the balance, access calibration mode, establish zero with an empty pan, then place the selected external weight on the pan. The manual advises using a calibration weight greater than two-thirds of capacity; MNM lists 100 g as the factory calibration-weight setting for the EJ-123, which satisfies that rule. For routine verification, use a clean, known weight and record the result before changing calibration. If verification error is repeatable, confirm level, drafts, static and pan clearance before recalibrating.
Connectivity options
A&D lists optional Quick USB, RS-232C and Bluetooth communication for the EJ family. The EJ-02, EJ-03 and EJ-27 interfaces are mutually exclusive, so only one of those interface options is installed at a time. The EJ-03 or wireless path can support documented GLP/GMP/GCP/ISO-style output workflows. This is useful when the balance is being used for quality records, teaching labs or repeated production checks where manually typing every weight creates unnecessary transcription risk.
Who should choose the EJ-123?
Choose the EJ-123 when 1 mg readability is important and the samples are comfortably below 120 g. It is a particularly practical fit for educational laboratories, jewelry components, small mechanical parts, pigments, powders, adhesives, formulation ingredients and comparative testing. If the routine samples frequently exceed 120 g, the EJ-303 provides the same 0.001 g readability with a higher 310 g capacity. If 0.01 g readability is sufficient, larger-capacity EJ models may provide a better capacity-to-cost fit.
FAQ
Is the A&D EJ-123 a 0.001 g balance?
Yes. A&D and MNM both publish the EJ-123 as a 120 g balance with 0.001 g, or 1 mg, readability.
Does the EJ-123 include a draft shield?
The EJ-123 uses the EJ-series breeze break intended for the 1 mg models. This is important because small air currents can disturb milligram-level readings.
Can the EJ-123 run on batteries?
Yes. A&D supports four AA batteries in addition to AC operation. MNM publishes approximately 70 hours with alkaline cells when the backlight is off.
Can the EJ-123 count small parts?
Yes. It supports ACAI parts counting with 5, 10, 25, 50 or 100-piece samples and a published 0.001 g minimum unit weight. Real-world counting accuracy still depends on how uniform the parts are.
Does the EJ-123 have internal calibration?
No. It is an external-calibration balance. A known external mass is used to calibrate the span.
Can it connect to a computer?
Yes, with optional interfaces. A&D lists Quick USB, RS-232C and Bluetooth options for the EJ family, with the limitation that those interface options are not installed simultaneously.
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