The Ultimate Us Coin Sizing Guide: Diameter, Thickness, and Millimeter Specs

Dive deep into The Ultimate Us Coin Sizing Guide: Diameter, Thickness, and Millimeter Specs with our latest coverage.

Q1: What is the exact diameter of a US dime in millimeters?
The official diameter is 17.91 mm, which equals 0.705 inches. It is the smallest diameter of all currently circulating United States coins.

Q2: How thick is a standard US dime in millimeters?
A standard US dime measures 1.35 mm thick at the raised outer rim (0.053 inches). The interior design basin sits between 1.15 mm and 1.25 mm.

Q3: How many dimes lined up edge-to-edge equal one meter?
Dividing 1,000 millimeters by 17.91 mm yields 55.83 dimes. Lining up 56 uncirculated dimes end-to-end spans 1,003 mm, overshooting one meter by just 3 millimeters.

Q4: Why is a dime physically smaller than a penny?
Historical currency laws required coins to reflect their value in precious metals. In 1792, ten cents of silver required much less physical volume than one cent of pure copper. When both denominations transitioned to base metals in the 20th century, the Treasury retained their established diameters to prevent public confusion and avoid refitting commercial coin machines.

Q5: Can I use pre-1965 silver dimes for metric measurements?
Pre-1965 Roosevelt and Mercury dimes share the same official 17.91 mm diameter and 1.35 mm thickness as modern clad coins. However, their 90% silver and 10% copper composition gives them an uncirculated mass of 2.500 grams, making them roughly 10% heavier than modern 2.268-gram clad versions.