U.S. coin size chart
The dime is the smallest U.S. coin at 17.91 mm across and the half dollar the largest at 30.61 mm (U.S. Mint).
| Coin | Diameter | Thickness | Weight | Composition | Edge |
|---|---|---|---|---|---|
| Dime | 17.91 mm (0.705 in) | 1.35 mm | 2.268 g | 8.33% nickel, 91.67% copper (cupro-nickel clad) | 118 reeds |
| Penny | 19.05 mm (0.75 in) | 1.52 mm | 2.5 g | 2.5% copper, 97.5% zinc (copper-plated zinc) | Plain |
| Nickel | 21.21 mm (0.835 in) | 1.95 mm | 5 g | 25% nickel, 75% copper | Plain |
| Quarter | 24.26 mm (0.955 in) | 1.75 mm | 5.67 g | 8.33% nickel, 91.67% copper (cupro-nickel clad) | 119 reeds |
| Dollar Coin | 26.49 mm (1.043 in) | 2 mm | 8.1 g | 88.5% copper, 6% zinc, 3.5% manganese, 2% nickel (manganese-brass clad) | Lettered |
| Half Dollar | 30.61 mm (1.205 in) | 2.15 mm | 11.34 g | 8.33% nickel, 91.67% copper (cupro-nickel clad) | 150 reeds |
The chart lists the circulating coins in order of diameter. A dime is smaller than a penny even though it is worth more, because coin size does not follow value.
Diameter, thickness, weight, composition and edge come from the U.S. Mint coin specifications page. For one coin, open its own page; for the weight of many coins, use the coin weight calculator.
Frequently asked questions
What is the smallest U.S. coin?
The dime, 17.91 mm across.
What is the biggest U.S. coin?
The half dollar, 30.61 mm across.
Is a dime smaller than a penny?
Yes: 17.91 mm against 19.05 mm.
Sources: U.S. Mint, Coin Specifications. Checked 2026-11-12. Figures described as "about" or "roughly" are arithmetic on these sources.
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General information only. Weights, sizes and counts come from the sources shown on each page and may change; check with your bank or the issuer before you rely on them. Nothing here is financial advice.