Three numbers get blurred in scale marketing. Capacity is the most it can weigh. Resolution is the smallest step the display shows. Accuracy is how far the reading may be from the true weight. Only the last one tells you how much to trust the number.
The three numbers
Illustrative. Display steps (resolution) show how finely a scale reads; a published tolerance shows how far the reading may be from the true weight.
Term
Also called
Example
What it tells you
Capacity
Max load
25 lb
The heaviest item the scale is rated for
Resolution
Increment, graduation, readability, division
0.1 oz
How finely the display steps
Accuracy
Tolerance, ± error
±0.2 oz
How far the reading may be from the true weight
A scale can display 0.1 oz steps and still be off by more than 0.1 oz. Resolution is a display property; accuracy is a performance promise—and most makers don't make one.
Real examples from spec sheets
DYMO M25: 25 lb capacity, 0.1 oz increments, and a published tolerance: ±0.2 oz below half capacity, ±0.4 oz above.
DYMO S100 (shipping scale): 100 lb capacity, 0.2 lb increments, ±0.4 lb tolerance in DYMO's guide. (DYMO's product page showed this series out of stock when we checked, so we don't review it.)
My Weigh Ultraship U2: two ranges—0.1 oz, then 0.2 oz—with no tolerance published.
Rollo shipping scale: Rollo lists "Accuracy: 0.07 oz / 2 g." That figure looks like the display step, not a tolerance.
Brecknell PS-USB-150: 150 lb × 0.05 lb divisions and NTEP approval. For NTEP-approved scales, allowable error is set by the certification class rather than a single ± figure on the spec sheet.
Why multi-range increments exist
Many scales show finer steps at low weights and coarser steps higher up (the U2 switches from 0.1 oz to 0.2 oz). That keeps the display honest about precision across a wide capacity. When a spec lists two increments, assume the finer one applies only to the lower range.
What to do with a tolerance
If a scale's tolerance is ±0.2 oz and your packed parcel reads 15.9 oz, the true weight could be 15.7–16.1 oz. Near a price break, leave that margin or round up. No scale prevents carrier adjustments; carriers use their own measurements.
Checking your scale
Follow the maker's calibration instructions. DYMO says the M25 is factory calibrated and won't need recalibration; Brecknell, My Weigh and Accuteck document user calibration.
A known reference weight is the fairest check. Brecknell's PS-USB calibration needs more than 10% of capacity as a test weight.