Calibration Weights: Which Weights Fit Your Scale, by Capacity and Readability
Reviewed by MNM Scales technicians · Updated November 2, 2026 · Prices checked November 2, 2026
Short answer: choose calibration weights from two numbers on your scale: its capacity and its readability. You want one weight at or near capacity for the span check, smaller weights for the middle and low end of the range, a weight of more than a third of capacity for the corner test, and weights accurate to about one third of the readability, which is what A&D recommends. For a 220 g or 320 g x 0.1 mg balance, that is the A&D AD-200-20-2 Cal-Pal kit ($659): 200 g, 20 g and 2 g, with a calibration certificate. Call (832) 290-3120 with your model and we will match the weights to it.
This guide is for lab, QA and production staff who check their own scales and balances between calibrations: which mass values to buy, how many weights each check needs, and when a single weight, a three-weight kit or a full set makes sense. MNM Scales has sold, calibrated and repaired scales and balances for over 30 years from our shop in Cypress, Texas. If you need to know the accuracy limits for each class, our guide to calibration weight classes covers that; this page covers which weights fit which scale.
How to choose calibration weights by capacity and readability
- Read the capacity and readability from the nameplate or the manual, for example 220 g x 0.1 mg or 320 g x 0.001 g.
- Span: pick one weight at or near capacity. If the balance has external calibration, use the exact value its manual lists for the calibration routine. See internal vs external calibration balances for how the two routines differ.
- Middle and low end: add a weight around a tenth of capacity and a small weight near the smallest loads you weigh. A&D builds its Cal-Pal kits this way: 200 g, 20 g and 2 g for a 220 g balance, or 5 g, 500 mg and 1 mg for a 5 g microbalance.
- Corner (eccentricity) test: A&D’s method uses one weight of more than a third of capacity, placed in the center and then in the center of each quarter of the pan. On a 220 g balance, a 100 g or 200 g weight works.
- Repeatability: load the same weight several times, for example ten, and work out the standard deviation of the readings. Any single weight in the working range will do.
- Accuracy of the weight: A&D recommends a test weight with an accuracy of one third of the balance readability, so a finer balance needs a finer weight. Our weight class guide turns that into a class.
Bench and floor scales follow the same idea with much larger test loads. For those, book our scale calibration service in Houston.
Which A&D Cal-Pal kit fits your balance
A&D publishes which three-weight Cal-Pal kit goes with each of its balances. The largest weight sits at or just under capacity. The kits in stock at MNM Scales:
| Kit | Weights | A&D balances A&D pairs it with | Price |
|---|---|---|---|
| A&D AD-5-500-1 | 5 g, 500 mg, 1 mg (ASTM Class 0) | BM-5 and BM-20 microbalances | $91.17 |
| A&D AD-100-10-20 | 100 g, 10 g, 20 mg | HR-100A/AZ, GH-120, GF-124A, GX-124A, EK-120i | $659 |
| A&D AD-100-10-200 | 100 g, 10 g, 200 mg | HR-150AZ, EW-150i, GF-123A, GX-123A, FX-120i, FZ-120i | $659 |
| A&D AD-200-20-20 | 200 g, 20 g, 20 mg | GH-202, GH-252, GR-202 | $659 |
| A&D AD-200-20-200 | 200 g, 20 g, 200 mg | GR-200, GR-202, GF-224A, GX-224A, HR-250A/AZ | $659 |
| A&D AD-200-20-2 | 200 g, 20 g, 2 g | BM-200, BM-300, GR-200, GR-300, GF-324A, GX-324A, FX-200i, FX-300i, FZ-200i, FZ-300i | $659 |
| A&D AD-500-50-200 | 500 g, 50 g, 200 mg | BM-500, GF-603A, GX-603A, FX-500i, FZ-500i | $136.05 |
Not on the list? Use the same pattern: the largest weight at or just under capacity, then one about a tenth of it, then a small one. Call us with the model and we will confirm the values.
Single weights, kits or sets
A&D sells test weights three ways, and each suits a different job:
- Single weight: one piece in a vial or soft case with a cotton glove. Best for a daily or weekly check at the one value your procedure uses, or for the external calibration routine of one balance.
- Cal-Pal kit (three weights): a large, middle and small weight in a vial or hard case, with a glove set and tweezers or a lifter. Covers span, middle and low-end checks for one balance size.
- Weight set (9 to 21 pieces): built in a 5-2-2-1 or 5-3-2-1 pattern, so the pieces combine to cover many values across the range. Use a set for full linearity tests across the range or when a lab checks many balance sizes.
Single weights in stock: Rice Lake 50 g ($92.99), Rice Lake 100 g ($108.99) and Rice Lake 200 g ($126.99), all ASTM Class 1 polished stainless steel with a case and glove, and the MNM Scales 500 g Class I weight ($249).
Calibration weights in stock
| Weight or kit | Masses | Certificate | Price |
|---|---|---|---|
| A&D AD-5-500-1 kit, ASTM Class 0 | 5 g, 500 mg, 1 mg | Calibration certificate included | $91.17 |
| A&D AD-500-50-200 kit, ASTM Class 1 | 500 g, 50 g, 200 mg | Calibration certificate included | $136.05 |
| A&D AD-200-20-2 Cal-Pal kit | 200 g, 20 g, 2 g | Calibration certificate included | $659 |
| A&D AD-200-20-200 Cal-Pal kit | 200 g, 20 g, 200 mg | Calibration certificate included | $659 |
| A&D AD-200-20-20 Cal-Pal kit | 200 g, 20 g, 20 mg | Calibration certificate included | $659 |
| A&D AD-100-10-200 Cal-Pal kit | 100 g, 10 g, 200 mg | Calibration certificate included | $659 |
| A&D AD-100-10-20 Cal-Pal kit | 100 g, 10 g, 20 mg | Calibration certificate included | $659 |
| Rice Lake 12948, ASTM Class 1 | 200 g, with case and glove | Certificate not included; ask us | $126.99 |
| Rice Lake 12946, ASTM Class 1 | 100 g, with case and glove | Certificate not included; ask us | $108.99 |
| Rice Lake 12964, ASTM Class 1 | 50 g, with case and glove | Certificate not included; ask us | $92.99 |
| MNM Scales 500 g, Class I | 500 g | Certificate not included; ask us | $249 |
Handling and storing test weights
- Handle weights with gloves, tweezers or a lifter. A&D advises against bare hands, which contaminate and warm the weight.
- Let weights reach room temperature before a check. A&D suggests leaving them in the lab from the day before.
- Check on a level, solid bench away from drafts, vents and sunlight, and give the balance its warm-up time first.
- Keep each weight in its case, and keep the certificate with your balance records.
Rules: test weights, records and Texas trade scales
Write your check procedure down: which weights, at which points, how often, and the limits that trigger a call for service. Keep the weight certificates on file and send weights back for recalibration on the schedule your quality system sets; see how often a scale should be calibrated. When a scale is used in trade, such as selling by weight, it also has to be legal for trade in Texas. TDA does not require an NTEP certificate for every device, but the scale must meet NIST Handbook 44 and suit its use; some scales do need one, so we recommend NTEP models and can check yours. Our TDA-registered technicians can place trade scales in service. See our NTEP guide and TDA scale certification guide.
Calibration and rental
- Balances up to 2.2 kg: in-house calibration with a certificate ($95) or NIST calibration with a NIST-traceable certificate ($395).
- Balances 2.2 to 6.2 kg: in-house calibration ($195) or NIST calibration ($495).
- Scales and balances 6.2 to 35 kg: in-house calibration ($250) or NIST calibration ($595).
- On-site service: $295 + $2 per mile per visit across the Houston area, with calibration charged per scale; see on-site calibration in Houston and balance calibration in Houston.
- Certificates: see NIST vs in-house certificates.
- Mail-in, repairs and rentals: send a scale for mail-in calibration, have us repair the brands we sell, and rent all types of scales.
Not sure which weights fit? Send the make, model, capacity and readability of each scale or balance you check, and the checks your procedure calls for. We will match the weights and quote calibration with them. Shop: 21249 FM 529 Rd, Cypress, TX 77433, visits by appointment.
Frequently asked questions
What calibration weights do I need for my scale?
Start from the capacity and readability. Use one weight at or near capacity for span, a middle and a small weight for the rest of the range, and weights accurate to about one third of the readability.
How many calibration weights do I need?
One weight covers a daily span or repeatability check. Three weights, as in an A&D Cal-Pal kit, cover the top, middle and low end of the range. A full set covers linearity at many points.
What weight do I use for a corner test?
A&D’s method uses one weight of more than a third of the balance capacity, placed in the center and then in the center of each quarter of the pan.
Which weight kit fits a 220 g analytical balance?
A&D pairs its AD-200-20-2 Cal-Pal kit (200 g, 20 g and 2 g) with the BM-200, BM-300, GR-200 and GR-300 and with FX-200i and FX-300i balances.
Do the A&D weight kits come with a certificate?
Yes. The A&D kits we stock ship with a calibration certificate. The Rice Lake and MNM single weights do not include one; ask us if your procedure needs it.
Should I buy a single weight or a weight set?
Buy a single weight for routine checks at one value. Buy a set when you test linearity across the range or check several balance sizes, since the pieces combine to cover many values.
Can MNM Scales calibrate my balance instead?
Yes. We calibrate balances in-house with a certificate or with a NIST-traceable certificate, in our Cypress shop, by mail-in, or on-site across Greater Houston for $295 + $2 per mile per visit.