⚖️ Coin Weight Verification Calculator

Enter your coin's measured weight and its official specification weight to see the percent deviation — a large deviation can be a first flag for further authentication, though it is not proof of authenticity on its own.

Measured weight (g)

Official spec weight (g)

How the deviation is worked out

The tool compares your scale reading against the coin's published standard and expresses the gap as a share of that standard:

deviation % = (measured - spec) / spec × 100

The figures on load are a clad quarter: 5.60 g measured against a 5.670 g standard. The gap is -0.07 g, and -0.07 / 5.670 is -0.01235, so the tool shows -1.23%. A negative result means the coin is light, a positive one that it is heavy. Grams in, grams out - the ratio is the same whichever unit you use, as long as both boxes use it.

Standard weights and normal slack

Current United States circulating coinage, with the Mint's weight tolerance:

Coin	Spec	Tolerance
Cent, 1982 to date	2.500 g	±0.100 g
Nickel	5.000 g	±0.194 g
Dime, clad	2.268 g	±0.091 g
Quarter, clad	5.670 g	±0.227 g
Half dollar, clad	11.340 g	±0.454 g

Pre-1965 silver runs heavier - 2.500 g dime, 6.250 g quarter, 12.500 g half - so check the date before choosing a spec. Circulation wear only ever removes metal, which is why worn coins read light and a distinctly heavy coin is the more interesting result.

Weight is a screening check, not authentication. Good counterfeits match the standard, so a pass clears nothing; measure diameter, thickness and edge as well. Use a scale that reads to 0.01 g - a 0.1 g kitchen scale cannot resolve 1% on a 2.5 g cent.

Frequently asked questions

How much should a US quarter weigh?

A clad quarter from 1965 on weighs 5.670 g, with a Mint tolerance of 0.227 g either way, or about 4%. A pre-1965 90% silver quarter weighs 6.250 g.

What deviation is too much?

Anything inside the Mint tolerance is normal, and a circulated coin a percent or two light is just wear. Treat a reading several percent off, especially a heavy one, as a reason to check the coin's other dimensions.

Why does the result jump to a huge number?

An empty spec box falls back to 0.001 g, and dividing by that produces a deviation in the hundreds of thousands of percent. Type a real standard weight and it returns to normal.