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.

Design Offset Millimeters (mm)

Required number input.

Planchet Diameter Millimeters (mm)

Required number input.

Express measured strike-center displacement as a percentage of planchet diameter; this is not a grading-service label. 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]

Linear Offset Percent (%)

The resulting linear offset 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.

• Precious Metal Allocation Percent

  Find precious-metal holdings as a share of a supplied portfolio value; this is not an allocation recommendation.

• Bid Ask Spread Percent

  Calculate quoted bid-ask spread as a percentage of the midpoint, not the bid.

• Cleaned Coin Market Hit Percent

  Measure a cleaning-related observed price difference using otherwise comparable coins; not a universal market discount.