Use this numismatic calculation to document a collection, metal content, historical denomination, minting error, grading cost, auction price, or market scenario with explicit measurements and prices.

Struck Diameter Millimeters (mm)

Required number input.

Normal Diameter Millimeters (mm)

Required number input.

Compare broadstruck coin diameter with the issue's normal diameter. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Diameter Expansion Percent (%)

The resulting diameter expansion percent returned as a number.

• Coin value and attribution depend on authenticity, date, mint, variety, grade, surfaces, provenance, market liquidity, fees, metal assay, and current spot prices. Images and arithmetic cannot replace expert authentication or in-hand grading.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Retain weight, diameter, photographs, references, transaction fees, and price dates; verify valuable pieces with recognized catalogues and qualified independent experts.

• Premium Over Spot Percent

  Compare a coin's asking price with its metal value; a negative result is a discount.

• Tube Capacity By Diameter

  Estimate a single vertical stack's capacity from tube length and coin thickness; diameter only checks fit.

• Album Page Slot Capacity

  Count coin-album slots from a rectangular row-by-column layout.