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

Everything you need to know about The Ultimate Us Coin Sizing Guide: Diameter, Thickness, and Millimeter Specs, covering critical updates.

While Mint specifications set a rigid target, real-world circulation degrades physical dimensions over time. As coins circulate through cash registers, pockets, and industrial sorting hoppers, microscopic layers of the cupronickel cladding scrape away.

A heavily worn dime, graded "Good" (G-4) or "Very Good" (VG-8) on the numismatic Sheldon scale, routinely sheds 0.05 mm to 0.12 mm in outer rim thickness. The diameter shrinks far more slowly because radial rim impact tends to flatten rather than shear the edge, but extensive wear can still reduce overall diameter down to roughly 17.80 mm.

Mass drops noticeably faster than diameter. A coin that has circulated for twenty to thirty years often weighs between 2.15 and 2.22 grams, reflecting a net metal loss of 2% to 5%. For precision tasks, avoid using heavily tarnished, smooth-rimmed specimens. Choose a piece struck within the past five years displaying crisp reeding and sharp rim definition.