Free online tachymeter calculator and simulator. Instantly convert elapsed time into units per hour — exactly how the tachymeter scale works on a Rolex Daytona, Omega Speedmaster and other chronographs.
Tachymeter scales usually work between \~7.2 and 60 seconds (500 to 60 units/hour).
A tachymeter scale converts the time it takes to travel a fixed distance (usually 1 kilometre or 1 mile) into speed in units per hour.
Formula: Units per hour = 3600 ÷ elapsed seconds
What is a tachymeter on a watch? It is a scale (usually on the bezel or chapter ring) that lets you convert elapsed time into average speed or production rate per hour.
How do I use a tachymeter on a Rolex Daytona or Omega Speedmaster? Start the chronograph when you pass a starting point. Stop it after exactly 1 km or 1 mile. The second hand will point to your average speed on the tachymeter scale.
What range does a typical tachymeter cover? Most tachymeter scales run from about 60 to 500 units per hour, corresponding to elapsed times between 60 seconds and 7.2 seconds.
Can I use it for things other than speed? Yes. Any event that repeats at a steady rate (production units, heartbeats, etc.) can be measured the same way.