To calibrate a shipping scale: clean the platform, power on and wait 60 seconds away from running printers, press Tare to zero, hold CAL or MODE until the display shows the required weight, place the exact weight in the centre, wait for PASS, then verify with a known package. No calibration weight? Use nickels for small scales, or sealed bags of sugar for larger ones.
Why shipping scales lose calibration
An inaccurate shipping scale costs money in two directions. Overweight readings mean you overpay postage on every package. Underweight readings mean packages get returned or held for additional fees — which costs time, customer relationships, and often more than the original postage.
Shipping scales sit in busy environments: packing benches next to label printers, tape dispensers, and box cutters. The constant vibration from a label printer running 50 labels an hour transmits directly into the load cell through the desk surface. This is the most common cause of gradual drift in e-commerce shipping scales.
Packing tape residue is a close second. A small piece of tape stuck to the underside of the platform adds a consistent false weight — often 2–5g — to every reading. It’s invisible, consistent, and easy to miss.
Large-capacity shipping scales (30lb+) are also more vulnerable to overload damage than smaller scales. Dropping a heavy parcel on the platform can permanently shift the load cell. If your scale was accurate and suddenly isn’t after a drop, calibration may not fix it.
What you need before you start
- A flat, stable surface away from printers. Move the scale at least 50cm from any running printer before calibrating. Printer vibration is the single most common cause of calibration failure on shipping scales.
- Fresh batteries or a reliable power source. USB-powered scales are less prone to battery drift but still need a stable power connection.
- The correct calibration weight. Shipping scales typically calibrate at their maximum capacity — a 30lb scale needs a 30lb weight, a 5kg scale needs 5kg. Check the bottom of the scale or the manual. See our calibration weights guide for sourcing options.
- A clean platform. Check for tape residue, packing foam fragments, and anything stuck underneath the platform before starting.
How many coins do you need?
Nickels work for small shipping scales (under 1kg capacity). For larger scales, a sealed 1kg or 2kg bag of sugar or rice with its net weight printed on the packet is a practical substitute. The printed net weight is typically accurate to ±2g — good enough for most shipping use.
Coin calibration weight calculator
For small shipping scales only. Enter the required calibration weight in grams.
100
US nickels
For scales over 1kg: use sealed bags of sugar or rice as a substitute. A 1kg bag = 1000g reference. More practical than stacking 200 nickels.
A factory-sealed 1kg bag of granulated sugar makes a reliable 1000g calibration reference for shipping scales. The net weight printed on the packet is accurate to ±2g. Use it straight from the shop — once opened, moisture changes the weight. For the coin alternative on any target, use the coin calibration calculator →
Step-by-step calibration
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Clean the platformWipe the platform with a dry cloth. Check underneath for tape residue, foam, or anything stuck to the underside. Lift the platform if it’s removable and clean the area underneath. Even a small piece of tape causes a consistent false reading on every package.
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Move away from printers and power onMove the scale at least 50cm from your label printer. If your scale is USB-powered, plug it in and let it stabilise for 60 seconds. Battery-powered scales: replace batteries if they haven’t been changed in 6 months, then power on and wait 60 seconds.
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Zero the scaleNothing on the platform. Press Tare or Zero. Wait for a stable 0.0 reading. If it drifts or won’t hold zero, check for tape residue underneath and make sure the scale is on a completely flat surface before continuing.
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Enter calibration modeSee the brand table below. Most shipping scales respond to holding
CALorMODEfor 3–5 seconds until the display showsCAL. Some Ohaus Courier models have a dedicated CAL button. The display will show the required calibration weight — this is what you place on the platform next. -
Place the calibration weightPlace the calibration weight gently in the centre of the platform. Do not drop it — impact can shift the load cell on larger scales. Do not bump the desk or scale while waiting for the reading to stabilise.
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Confirm and verifyWait for
PASSor automatic return to weighing mode. Remove the weight and re-zero. Verify by weighing a package with a known weight — a sealed 1kg bag of sugar or a confirmed-weight parcel. If the reading is off by more than your scale’s stated tolerance, repeat from Step 2.
Button sequences by brand
| Brand / model | Calibration sequence | Display shows | Required weight |
|---|---|---|---|
| Ohaus Courier 1000 / 3000 / 5000 | Press and hold CAL button until display responds |
CAL → place weight → PASS |
Max capacity (1kg, 3kg, or 5kg) |
| Stamps.com / ShipStation USB scales | Varies by model. Most: hold TARE + ON/OFF |
CAL → flashes required weight |
Max capacity |
| American Weigh Scales (AWS) shipping series | Press ON/OFF → hold MODE 3–5 s |
CAL → flashes weight → PASS |
Capacity dependent |
| Bonvoisin parcel scale | Hold CAL while powering on |
CAL → place weight → PASS |
Max capacity (check base) |
| Dymo shipping scales | No user calibration on most models. Factory set. | N/A | Contact Dymo support |
| Generic USB shipping scale | Hold MODE 3–5 seconds |
CAL → flashes target weight |
Max capacity (check base of scale) |
Is your shipping scale accurate?
A calibration that passes doesn’t guarantee accuracy — it only means the scale accepted the input. Always verify with a known-weight reference after calibrating.
Scale accuracy test
Good reference objects: a sealed 1kg bag of sugar, a 500g bag of rice, or a confirmed-weight parcel.
For a more detailed test with pass/fail breakdown, use the full accuracy tester tool →
Troubleshooting
| Symptom | Most likely cause | Fix |
|---|---|---|
| Reads consistently high by same amount | Tape residue or debris under platform | Clean underside of platform thoroughly; re-zero; recalibrate |
| Readings jump while package sits on scale | Printer vibration through desk | Move scale away from printer; place on anti-vibration mat |
Shows OVER or ERR |
Package exceeds maximum capacity | Remove immediately; check scale’s max capacity and use a higher-capacity scale |
Shows Lo or battery symbol |
Low battery | Replace or recharge before doing anything else |
| USB scale reads zero on computer but not on scale display | Software / driver issue, not a calibration issue | Reinstall scale driver; check ShipStation / Stamps.com USB scale settings |
| Calibration completes but readings still wrong | Calibration weight itself was inaccurate | Repeat with a verified weight — sealed bag of sugar or certified calibration weight |
| Scale was dropped and now reads incorrectly | Load cell physically shifted | Try calibrating once. If still wrong after two attempts, the load cell is likely damaged — replacement is usually more cost-effective than repair. |
How often to calibrate
For e-commerce businesses shipping daily: calibrate monthly and spot-check weekly by weighing a known-weight package before your first dispatch of the day.
For occasional use: calibrate every 3–6 months.
Always calibrate after:
- Moving the scale to a new location or surface
- Replacing batteries or changing power source
- A drop or heavy impact
- Packages being returned for insufficient postage
- Noticing consistent weight discrepancies
If you ship more than 100 packages daily and your postage costs suddenly jump without a rate increase, check your scale first. A consistent 5g overread on 100 packages per day adds up to real money over a month. Calibrate and compare your postage costs before and after.
Frequently asked questions
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