Is your kitchen scale measuring correctly?

You find out whether your scale measures correctly by testing it against something whose weight is known. The easiest reference is the net quantity printed on an unopened package; net quantity is one of the details that must appear on the label. The second test needs no reference at all: you weigh the same thing several times in a row and see whether the scale repeats itself.

Why a scale rather than household measures?

TÜBER, Türkiye's national dietary guideline, has taken measurements on this. The volume of tea glasses on the market varies between 85-165 mL, water glasses between 200-560 mL, and bowls between 130-600 mL. The tablespoon is not fixed either; its volume has been found to drop from 15 mL to 10-12 mL. As an international reference the guideline takes 1 cup as 240 mL, but there is no guarantee that the glass in your kitchen equals that.

“One glass” does not correspond to a single amount within these ranges. A scale closes that uncertainty — but only if it measures correctly itself. A scale that measures wrong is more misleading than a variable glass, because the number it gives carries an impression of precision.

How do you test the scale?

First put it on a flat, hard surface. The edge of the counter, the top of the dishwasher or a soft mat will spoil the reading. Then weigh an unopened package and compare it with the net quantity on it. What you are looking for is not an exact match; the contents of the package may not be exactly the value printed, but a large difference comes from the scale.

Then look at three things. When you lift the same package and put it back, does the scale show the same number? When you put two of the same package on, does the reading come out close to double? When you slide the package from the middle of the platform to the edge, does the number change? If it is consistent on all three, you can trust the scale.

Do not leave the test at a single weight. Scales generally work within a range, and a device that measures well at low weights can drift with a heavy pot. If you have sealed packages of two different weights, try both; if both hold, your confidence is far more solid.

What does a drift mean?

There are two kinds of drift and their consequences differ. A constant drift appears in the same direction and by the same amount at every measurement; if the scale always makes the same error you can carry on comparing, because your measurements stay consistent relative to one another.

A random drift gives a different number every time. There is no way to correct this at home, and a measurement from that scale carries no information. The most frequent cause of random drift is a dying battery; changing the battery and repeating the test is the first thing to try.

When do you check again?

Repeat the test when you change the battery, when the scale falls on the floor, when liquid is spilled on it, and after it has been moved. Apart from these, checking once now and then with a known package is enough. The test takes a few minutes, and if you note the result down you will know what to compare it against next time.

There is also this: the smallest value the scale can show has to suit what you want to weigh. Weighing spices or yeast with a scale that does not show below a gram is not the scale's error but the tool not suiting the job. In the same way, a scale with a low upper limit cannot weigh a full pot.

Watch the scale's own behavior during the test as well. Some scales move the number around for a while after the weight is put on and then settle it; the reading has to be taken after it settles. If the number never settles, that is a result too.

What can you do today?

Take an unopened package from the kitchen and put it on the scale; compare it with the net quantity on its label. Lift the same package and put it back, then slide it to the edge of the platform. Place the scale somewhere flat and stable, and let it stay in the same place for every measurement; as its surface changes, so does its reading.