Horology glossaryDefined term / tachymeter
Tachymeter
A scale, usually printed on the bezel or dial edge of a chronograph, that converts elapsed time over a known distance into speed.
Authentication note
Why this detail matters.
Tachymeter scale printing, spacing, and numerals closely follow the reference's original specification, and mismatched fonts, spacing errors, or an incorrect scale range on a bezel are common indicators of an aftermarket or incorrect part. It's a detail worth comparing to genuine reference photography during a case-level check.