US Coin Sizes: Diameter, Thickness and Weight

Every US coin is made to an exact specification published by the US Mint, so a coin makes a surprisingly good reference when you don’t have a ruler. These are the same sizes you’ll see listed as American coin sizes: the Mint publishes them in millimeters, and below each one is also given in inches and centimeters. Here are the official numbers, what they’re useful for, and a few measurements you can check yourself.

US coin sizes chart

Coin	Diameter	Diameter (inches)	Diameter (cm)	Thickness	Weight	Edge
Dime (10¢)	17.91 mm	0.705 in	1.79 cm	1.35 mm	2.268 g	118 reeds
Penny (1¢)	19.05 mm	0.750 in	1.91 cm	1.52 mm	2.500 g	Plain
Nickel (5¢)	21.21 mm	0.835 in	2.12 cm	1.95 mm	5.000 g	Plain
Quarter (25¢)	24.26 mm	0.955 in	2.43 cm	1.75 mm	5.670 g	119 reeds
Dollar coin ($1)	26.49 mm	1.043 in	2.65 cm	2.00 mm	8.100 g	Lettered
Half dollar (50¢)	30.61 mm	1.205 in	3.06 cm	2.15 mm	11.340 g	150 reeds

The inch values are converted from the Mint’s millimeter figures (1 inch = 25.4 mm) and rounded to three decimals. For centimeters, divide the millimeters by 10: a quarter is 2.43 cm across and a penny 1.91 cm.

To see any of these coins at its real size on your screen, open the actual size viewer and pick a coin. It includes the quarter, penny, dime, nickel, dollar coin and half dollar.

Using a coin as a ruler

• Penny = exactly ¾ inch. At 19.05 mm, the penny is the only US coin whose diameter is a round fraction of an inch. Four pennies laid edge to edge make exactly 3 inches.
• Quarter ≈ 1 inch. A quarter is 0.955 in, about 1/16 inch short of a full inch. Close enough to judge a screw or a button, not close enough for a woodworking cut.
• Nickel ≈ 21 mm, quarter ≈ 24 mm. Handy when a product lists a size in millimeters.
• Dime ≈ 1.35 mm thick. Useful for judging small gaps, such as the space under a door.

A coin is also a good way to calibrate an on-screen ruler. On any ruler on this site, tap Calibrate, choose a quarter or penny, and adjust until the circle on screen exactly matches the coin you’re holding. Coins are harder to line up than a credit card because they’re round, so check the match from directly above.

How tall is a roll or stack of coins?

Stack heights follow directly from the thickness in the chart. Real coins wear slightly, so an actual stack comes out a little shorter.

Standard bank roll	Coins	Value	Stack height
Pennies	50	$0.50	76.0 mm (2.99 in)
Nickels	40	$2.00	78.0 mm (3.07 in)
Dimes	50	$5.00	67.5 mm (2.66 in)
Quarters	40	$10.00	70.0 mm (2.76 in)

A stack of 10 quarters is 17.5 mm high, and 100 pennies weigh exactly 250 g (8.82 oz). To turn a weighed jar of sorted coins into a dollar value, use the coin value calculator.

Why the sizes don’t follow the value

The dime is the smallest coin even though it’s worth more than the penny and nickel. The first US dimes were made of silver, and the metal in a coin was once meant to be worth about its face value, so a ten-cent silver coin only needed to be small. When silver was removed from dimes and quarters in 1965, the Mint kept the same sizes so that vending machines and coin counters would still work.

What the coins are made of today:

• Penny: zinc with a thin copper plating (since 1982)
• Nickel: 75% copper, 25% nickel
• Dime, quarter and half dollar: layers of copper-nickel bonded to a pure copper core. You can see the copper stripe on the edge.
• Dollar coin: manganese brass over a copper core, which gives it its gold color

Measuring a coin yourself

To check an unknown or foreign coin, measure straight across its widest point with a millimeter ruler, or place it on our mm ruler after calibrating. Measure twice at right angles: a worn or bent coin may be slightly oval. To convert what you measured, use the mm to inches converter.