How Wide Is a Dime in Mm? Why This Tiny 17.91 Mm Coin Is Modern Science's Secret Ruler
By Maya Lin-Takahashi
Q1: How wide is a US dime compared to a 1-euro or 1-pound coin?
A1: A US dime (17.91 mm) is substantially smaller than European standard coins. The 1-euro coin measures 23.25 mm in diameter, while the British 1-pound coin measures 23.03 mm. The dime is closer in size to the European 2-cent coin (18.75 mm) or the UK 5-pence piece (18.00 mm).
Q2: Does surface wear reduce the width of an older dime?
A2: Circulation wear primarily reduces the relief depth and edge reeds before affecting the coin's outer diameter. However, heavily circulated dimes minted decades ago can drop by 0.05 mm to 0.15 mm in outer width and lose between 0.05 and 0.10 grams of mass due to metal erosion.
Q3: Can I use a pre-1965 silver dime for the same physical scale checks?
A3: A 90% silver dime retains identical diameter specifications (17.91 mm) as modern cupronickel coins. Its weight is slightly heavier at 2.500 grams (compared to 2.268 grams for modern clad dimes). For width-based measurements or macro photography, silver dimes work identically; for weight verification, adjust your calculations for the 2.50-gram baseline.
Maya is a hardware enthusiast who tests and reviews smart home devices, smartphones, wearables, and audio gear. She focuses on practical consumer value and build quality.
