Watch Bezel Speed/Distance Calculator

Replicate the calculations of tachymeter, telemeter, and pulsometer watch bezels. Enter your elapsed time to get instant results.

Tachymeter Speed Calculator

Calculate speed from elapsed time over a known distance, just like a tachymeter bezel.

seconds

Telemeter Distance Calculator

Calculate distance using the speed of sound, just like a telemeter bezel (e.g., lightning to thunder).

seconds
°C

Pulsometer Heart Rate Calculator

Calculate heart rate from a timed pulse count, just like a pulsometer bezel.

seconds
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Formula

Tachymeter: Speed = 3600 / Elapsed Seconds x Distance | Telemeter: Distance = Elapsed Seconds x Speed of Sound (343 m/s at 20°C) | Pulsometer: BPM = (Calibration Beats x 60) / Elapsed Seconds

Frequently Asked Questions

How does a tachymeter bezel work?
A tachymeter measures speed based on time over a known distance. Start the chronograph at the start of a measured mile or kilometer. Stop it at the end. The scale shows your speed: Speed = 3600 / elapsed seconds.
How does a telemeter bezel work?
A telemeter measures distance using the speed of sound. Start the chronograph when you see an event (lightning), stop it when you hear the sound (thunder). The elapsed time times the speed of sound gives you the distance.
How does a pulsometer bezel work?
Start the chronograph and count a set number of heartbeats (usually 15 or 30). Stop the chronograph when you reach the count. The pulsometer scale shows your heart rate in BPM using the formula: BPM = (beats counted x 60) / elapsed seconds.

Understanding Watch Bezels

Watch bezels are more than decorative elements. Functional bezels turn your timepiece into a calculating instrument, a tradition dating back to early 20th-century chronographs designed for doctors, pilots, and racing drivers.

Types of Functional Bezels

Tachymeter: The most common bezel scale, found on watches like the Omega Speedmaster and Rolex Daytona. Originally used for timing race laps, it calculates speed over a known distance.

Telemeter: Less common today, originally designed for artillery officers to measure the distance to a target. The Longines Heritage Telemeter and some Breguet models feature this scale.

Pulsometer: Designed for medical professionals to quickly measure a patient's heart rate. The scale is calibrated for counting a specific number of beats (usually 15 or 30).

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