US penny (1¢) Exact Size

A US penny (one cent) is 19.05 mm (0.75 in) in diameter, 1.52 mm thick, and weighs 2.5 grams. That weight applies to pennies minted since 1982, when the composition changed from 95% copper to copper-plated zinc. Pre-1982 pennies weigh 3.11 g.

This guide covers the exact penny dimensions, the 1982 weight change, how the penny compares to a nickel, dime, and quarter, and how it sizes up against a AA battery and a fingernail.

Quick Answer: How Big Is a Penny?

A US penny is 19.05 mm across, 1.52 mm thick, with a plain (smooth) edge. It weighs 2.5 g (post-1982, copper-plated zinc) or 3.11 g (pre-1982, 95% copper).

US Penny Dimensions at a Glance

• Diameter: 19.05 mm, the second-smallest US coin (only the dime is smaller)
• Thickness: 1.52 mm
• Composition: since 1982, 97.5% zinc with a 2.5% copper plating; before 1982, 95% copper
• A roll of 50 pennies is about 76 mm long and weighs 125 g (post-1982)
• Stack height: about 66 pennies make 100 mm

What Does a Penny Look Like in Size?

A penny is about the width of an adult’s smallest fingernail plus a little, and a bit smaller across than a 5 cent euro coin. Its 19 mm diameter is roughly the same as a standard shirt button. Eleven pennies laid edge to edge span about 210 mm, the width of a sheet of A4.

6 Everyday Comparisons for a US Penny

1. A US nickel (21.21 mm) is 2.16 mm larger across and twice the weight (5.0 g).
2. A US dime (17.91 mm) is 1.14 mm smaller and lighter (2.268 g), despite being worth ten times as much.
3. A US quarter (24.26 mm) is 5.21 mm larger and 5.67 g.
4. A AA battery (14.5 mm diameter) is narrower than a penny.
5. A standard shirt button (~18 – 20 mm) is about the same size.
6. A 1 euro cent coin (16.25 mm) is noticeably smaller.

US Penny Size in Different Units

The 1982 Weight Change

Until mid-1982 a penny was 95% copper and weighed 3.11 g. Rising copper prices pushed the metal value of the coin toward one cent, so the Mint switched to a zinc core with a thin copper plating, dropping the weight to 2.5 g. The size stayed the same. 1982 pennies exist in both compositions, so a 1982 penny can weigh either 3.11 g or 2.5 g, which is a quick way to sort them.

Common Mistakes When Comparing US Penny Dimensions

1. Assuming a penny weighs 2.5 g regardless of year. Pre-1982 pennies weigh 3.11 g.
2. Thinking the penny is the smallest US coin. The dime is smaller in both diameter and thickness.
3. Confusing size with value. The dime is smaller and lighter than the penny but worth ten cents.
4. Assuming the penny has a reeded edge. Its edge is plain; the dime and quarter are reeded.
5. Using an old penny’s weight for a coin-counting estimate. Modern rolls are calibrated to 2.5 g coins.

Frequently Asked Questions

What is the diameter of a penny?

19.05 mm (0.75 in).

How much does a penny weigh?

2.5 g for 1982-and-later pennies; 3.11 g for pre-1982 copper pennies.

How thick is a penny?

1.52 mm.

Why did the penny get lighter in 1982?

Copper became too expensive, so the Mint switched to a copper-plated zinc coin, cutting the weight from 3.11 g to 2.5 g.

Is the penny the smallest US coin?

No. The dime is smaller in diameter and thickness.

How many pennies are in a 100 mm stack?

About 66.

Final Takeaway

A US penny is 19.05 mm across, 1.52 mm thick, and 2.5 grams for coins minted since 1982; earlier copper pennies weigh 3.11 g. It is larger than a dime but smaller than a nickel or quarter, and it has a plain edge rather than a reeded one.