A scale that is slightly wrong is more troublesome than one that is obviously broken, because it produces confident errors. Checking accuracy takes a few minutes and is worth doing periodically rather than assuming.
How Digital Scales Work
Inside is a load cell: a metal element with strain gauges bonded to it. Applying weight deforms the element microscopically, which changes the electrical resistance of the gauges, and the electronics convert that change into a number.
That mechanism can drift over time, particularly after impacts, overloading, or significant temperature changes. It does not usually fail suddenly; it goes slightly wrong.
What Counts as Acceptable
For general kitchen use, a scale within one or two grams across the working range is entirely adequate. Flour measured two grams out changes nothing.
For precision work, coffee, yeast, spices, tighter accuracy matters, which is why models covering that range include calibration functions. Ranges spanning both categories, such as the Escali Scale lineup, separate general and precision models for this reason.
Checking With Known Weights
Coins are the most accessible reference, since their masses are specified.
- A UK one-pound coin weighs 8.75 g
- A UK two-pence coin weighs 7.12 g
- A UK ten-pence coin weighs 6.5 g
- A US nickel weighs 5.00 g
- A litre of water weighs approximately 1000 g
Stack several to test across the range, since a scale can be accurate at one weight and drift at another. Worn or dirty coins are slightly light, so use ones in reasonable condition.
Calibrating
Many precision scales have a calibration mode, usually entered by holding a button, requiring a reference weight of a specified mass. Calibration weights are inexpensive and considerably more accurate than coins.
Most general kitchen scales have no user calibration. Where one is consistently and significantly wrong, replacement is the practical answer.
The Usual Causes of Inaccuracy
Before concluding a scale has failed, check the obvious. Low batteries cause drifting and inconsistent readings far more often than mechanical faults. An uneven or flexible surface distorts the reading. Vibration from an extractor or a nearby appliance affects it.
Placing the scale on a chopping board, a folded cloth or a wobbly worktop is a frequent and easily fixed cause.
Overloading
Exceeding the maximum capacity is the most common way a scale is permanently damaged, and the damage is not always obvious. A load cell that has been deformed reads inaccurately afterwards.
Weighing a full stockpot on a five-kilogram scale is the standard way this happens. Check the rating and stay comfortably within it.
How Often to Check
For most kitchens, once or twice a year, and after any impact or after the scale has been stored. For anyone using it for something where accuracy genuinely matters, more often.
The check takes two minutes and removes a variable that would otherwise be invisible.