How Often Should a Scale Be Calibrated? Intervals by Use (Trade, Pharmacy, Lab, Industrial)
Short answer: most scales should get a certified calibration at least once a year, plus a calibration whenever the scale is installed, moved or put in a different environment. Scales used for trade, pharmacy, lab QC or heavy daily use are often calibrated every 6 months, or every 3 months under heavy use, and checked with a test weight daily or weekly in between. If an auditor, a quality system or a customer contract sets the interval, follow that.
There isn’t one calibration interval that fits every scale. A milligram balance in a pharmacy, a 300 lb shipping scale on a warehouse floor and a jewelry scale behind a pawn counter all drift for different reasons. Here’s how to set a schedule that keeps your weights right without paying for calibrations you don’t need.
When a scale always needs calibration
Manufacturers agree on these triggers. A&D’s manuals, for example, tell owners to calibrate when the balance is first used, after it has been moved, when the ambient environment changes, and on a regular schedule.
- New installation. Shipping, a new bench and local gravity all shift the span slightly. Calibrate where the scale will be used. Buying from us? Add calibration to the order and it arrives calibrated with a certificate.
- After a move. Even moving a balance to another room or another floor can change its reading.
- Environment changes. A new HVAC setup, a seasonal temperature swing or a new location near a door or vent.
- After an overload, a drop or a repair. A shock load can shift a load cell. Any repair to a load cell, cable or indicator should be followed by calibration.
- When a check fails. If a known test weight reads outside your tolerance, calibrate before using the scale again.
Recommended calibration intervals by use
These are practical starting points we see work for our customers. Adjust them based on your own check results: if a scale is always dead-on at calibration time, the interval can stretch. If it’s often out, shorten it.
| How the scale is used | Certified calibration | In-house check with a test weight |
|---|---|---|
| Legal for trade (selling by weight, shipping charges, gold buying) | Every 6 to 12 months, and whenever the seal is broken | Daily or weekly |
| Pharmacy, compounding, dispensaries | Every 6 to 12 months, or as your inspector or SOP requires | Daily, before use |
| Labs and manufacturing QC (ISO 9001, GMP, ISO/IEC 17025 programs) | At the interval set in your quality system, often 6 to 12 months | Daily or per batch |
| Warehouse, shipping and industrial floor scales | Every 6 to 12 months, more often with forklift traffic | Weekly |
| Crane scales and load cells used for lifting | At least yearly, and after any shock load | Before critical lifts |
| Reloading, jewelry, hobby and general testing | Every 12 months or when a check is off | Each session |
What makes a scale drift faster
- Heavy use. Thousands of weighings a day, or loads close to full capacity.
- Shock and overloads. Dropped parts, pallets set down hard, forklifts running onto floor scales.
- Temperature and humidity swings. Loading docks, outdoor scales and unconditioned shops.
- Washdown, dust and corrosion. Food plants, agriculture and chemical areas.
- Moving the scale. Portable and shared scales need calibration more often than ones that never leave the bench.
- Resolution. The finer the readability, the less drift it takes to show up. A 0.001 g balance needs more care than a 1 lb floor scale.
Calibration vs. a quick check: what’s the difference?
A check means placing a known certified test weight on the scale and confirming the reading is within your tolerance (see calibration weight classes to choose one). It takes a minute and changes nothing. A calibration adjusts the scale to the reference weights and is documented on a certificate. Daily or weekly checks tell you when you need a calibration, so you catch problems before they cost you product, money or an inspection.
Many balances let you run the check yourself. See our step-by-step guides for the A&D FX-120i, the A&D EK-1200i the LP7515 floor scale indicator, crane scales and floor scales. Not sure which certificate you need? See in-house vs NIST-traceable certificates.
Legal-for-trade and regulated scales
NIST Handbook 44 sets the tolerances commercial scales must meet, and state weights and measures programs inspect devices used in trade. The calibration interval itself usually comes from your own program, your SOPs or your auditor. In practice, a commercial scale that’s checked often and calibrated at least yearly is ready for inspection. When a sealed NTEP scale is adjusted, it must be calibrated and resealed by a registered service technician. MNM Scales is TDA licensed with registered technicians who calibrate and seal legal-for-trade scales and can place devices in service in Texas.
In-house certificate or NIST-traceable certificate?
- In-house calibration with certificate (from $95): calibrated with NIST-tested weights, with our calibration certificate. Great for most businesses, reloaders and general testing.
- NIST calibration with NIST-traceable certificate (from $395): for audits, quality systems, pharmacies, labs and contracts that ask for NIST traceability.
Calibration prices by capacity
The tier is based on your scale’s maximum capacity (the highest range on dual-range models). A capacity exactly at a limit stays in the lower tier. Full details are in our scale calibration cost guide.
| Maximum capacity | In-house calibration with certificate | NIST calibration with NIST-traceable certificate |
|---|---|---|
| Up to 2.2 kg (about 5 lb) | $95 (add to cart) | $395 (add to cart) |
| Over 2.2 to 6.2 kg | $195 (add to cart) | $495 (add to cart) |
| Over 6.2 to 35 kg | $250 (add to cart) | $595 (add to cart) |
| Over 35 to 150 kg | $350 (add to cart) | $750 (add to cart) |
| Over 150 kg (floor and large platform scales) | $495 (add to cart) | $995 (add to cart) |
Mail-in calibration is available nationwide and usually takes 1 to 3 business days in our Texas shop. Across the Houston area and suburbs we calibrate on-site for a $295 service call plus $2 per mile round trip. Our technicians bring their own test weights, so you don’t need to supply any. Dallas, Austin and San Antonio visits are available on request, and same-day or emergency calls depend on availability. Need a scale while yours is being serviced? We offer scale rentals too.
Put your scales on a schedule
Labs, warehouses, pharmacies and multi-location businesses can set up recurring calibration with us, so every scale is done on time and every certificate is on file before the auditor asks. MNM Scales has been in business for over 30 years, is one of the largest scale distributors in the country and is an authorized dealer for the brands we sell, so one call covers the scale, the calibration, the parts and the repair.
Ready to calibrate? Add your tier to the cart above, or request a quote for on-site visits and multi-scale schedules. Call (832) 290-3120. See all scale services.
Frequently asked questions
How often should a scale be calibrated?
Most scales should get a certified calibration at least once a year, plus a calibration whenever they are installed, moved or put in a new environment. Legal-for-trade, pharmacy, lab and heavy-use scales are often calibrated every 6 to 12 months, or every 3 to 6 months under heavy use, and checked with a test weight daily or weekly.
Do new scales need to be calibrated?
Yes. Calibrate a new scale where it will be used, because shipping and local gravity can shift the reading. MNM Scales can calibrate a new scale before it ships so it arrives with a certificate.
How often should I check my scale with a test weight?
Daily or before each use for pharmacy, lab and legal-for-trade scales, weekly for most industrial and shipping scales, and at each session for reloading and hobby scales.
How often do legal-for-trade scales need calibration?
Most businesses calibrate legal-for-trade scales every 6 to 12 months and check them often in between. A sealed NTEP scale that is adjusted must be calibrated and resealed by a registered service technician.
What causes a scale to need calibration more often?
Heavy use, shock loads and overloads, temperature and humidity swings, washdown or dust, frequent moves and very fine readability all make a scale drift faster.
How much does scale calibration cost?
At MNM Scales it depends on maximum capacity, from $95 (in-house certificate) or $395 (NIST-traceable certificate) up to 2.2 kg, to $495 or $995 for scales over 150 kg. Mail-in usually takes 1 to 3 business days.