How to Use a Tachymeter

A tachymeter measures speed over a known distance using a chronograph.

The method

1. Start the chronograph as you pass the start marker.
2. Stop it as you pass the end marker, exactly 1 kilometre or 1 mile away.
3. Read the bezel value pointed to by the seconds hand. That's your speed (km/h or mph).

Example

Cover 1 km in 30 seconds — seconds hand stops at "120" on the bezel. You were doing 120 km/h.

Limits

• Only works over a known distance.
• Can't time anything taking more than 60 seconds (bezel doesn't go that low).
• For production rates, set a 1-minute span and read units per hour.