To check a kitchen scale, put it on a hard flat surface, zero it, and weigh a US nickel, which should read 5 grams; then stack ten nickels for 50 grams and twenty for 100 grams to see whether the scale stays accurate as the load goes up.
You already own a set of test weights. They are in the coin jar.
A kitchen scale can be wrong for years without anyone noticing. Bread comes out a little dense, and the scale gets no blame because it shows a confident number every time.
Checking it takes two minutes and costs nothing. You need an object whose weight you already know, and the US Mint has been making those for a long time.
A US nickel is made to weigh 5.000 grams. That is a round number in the unit most kitchen scales use, which makes the nickel the handiest test weight in your house.
Other coins work too, as long as you know the numbers.
| Item | Weight | Notes |
|---|---|---|
| US nickel | 5.000 g | The best single test weight |
| US penny, 1983 or later | 2.500 g | Two of them make 5 g |
| US penny, 1981 or earlier | 3.11 g | Mostly copper, so heavier. Do not mix with newer ones |
| US dime | 2.268 g | Too light for most kitchen scales alone |
| US quarter | 5.670 g | Four quarters make 22.68 g |
| US paper bill, any value | About 1 g | Good for testing 1 g steps |
| 1 euro coin | 7.50 g | |
| 2 euro coin | 8.50 g |
Pennies dated 1982 can be either weight, because the Mint changed the metal partway through that year. Leave them out.
Use coins that look clean and not badly worn. Decades in pockets take a tiny bit of metal off, but not enough to matter here.
Twenty nickels cost one dollar, and a bank will hand you a roll of forty for two. A full roll is 200 g of coins, plus a gram or two of paper wrapper if you leave it on.
Most kitchen scales show whole grams. A scale like that can only round, so one nickel showing 4 or 6 is not proof of anything. The larger stacks tell you more.
A scale that reads 3% low on 100 g will call a 500 g bag of flour 485 g.
Coins get clumsy past a few hundred grams. For the range where you actually weigh flour and sugar, use water.
One milliliter of water weighs very close to one gram at room temperature. So:
This test is only as good as the lines on your jug, so treat it as a rough check, within 10 g or so. A stick of butter in the US is another easy one. It is sold as 4 ounces, which is 113 grams, without the wrapper adding much.
Sometimes. Try these in order.
If the error still grows with the load after all that, replace the scale or correct for it in your head.
A scale is the only honest judge of weight in most kitchens. Hands are bad at it, as we found in how well can you judge weight by hand, and eyes are fooled by shape.
That gap between what looks even and what weighs even is the whole idea behind Halfsies. Each day you get three hand-drawn objects and cut each one in half by eye. Then a scale weighs both halves and shows you how far off you were. The score for a cut is the lighter half divided by the heavier half, times 100, so a 48/52 split earns 92. You can try today's three cuts in your browser for free.
A US nickel weighs 5.000 grams when new. That round number is why it is the most common household test weight for a kitchen scale.
Twenty US nickels weigh 100 grams. Forty pennies dated 1983 or later also weigh 100 grams, since each one is 2.5 grams.
The usual causes are weak batteries, a soft or uneven surface, a draft, or placing the item off center. Change the batteries, move the scale to a hard flat counter and load it in the middle.
It depends on the year. US pennies dated 1983 or later weigh 2.5 grams. Pennies dated 1981 or earlier are mostly copper and weigh 3.11 grams. Pennies from 1982 can be either.