Check units: log length is in metres, diameter in centimetres. ISO uses the top-end diameter without bark. Follow the measurement method agreed for your timber.
Do not substitute a nearby size for a missing one. The calculator stops if a required value is unavailable. Agree on the table and rounding rules before using results for trading.
Length in metres × thickness in millimetres / 1000 × width in centimetres / 100. Separate widths with commas and use a dot for decimals.
Data has not been verified against the original standards.