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How to read a pulsometer
A pulsometer turns a chronograph into a heart rate meter without any electronics. Start the chronograph, count the stated number of beats, stop, and read off the dial. This works out the same maths for any graduation.
Heart rate
75
A pulsometer is a timing aid, not a medical device. Anything unusual should be checked with a proper monitor and a doctor rather than a watch dial.
How the scale works
A pulsometer scale is calibrated for a fixed number of pulsations, printed on the dial as something like graduated for 30 pulsations. That number is the whole design. The scale simply does the division for you.
The procedure is: start the chronograph as you begin counting heartbeats, count until you reach the stated number, then stop. Wherever the chronograph seconds hand has landed, the pulsometer scale next to it reads your heart rate directly in beats per minute.
The maths is straightforward. If a scale is graduated for 30 pulsations and 30 beats took 24 seconds, the rate is 30 divided by 24, multiplied by 60, which is 75 beats per minute. The printed scale is that calculation pre-solved at every point around the dial.
Why the graduation number matters
A scale graduated for 15 pulsations is faster to use, since you only count 15 beats, but it is less accurate. Any error in your counting or in when you stopped the chronograph is spread over fewer beats, so it has proportionally more effect on the result.
A 30 pulsation scale takes roughly twice as long and gives a correspondingly steadier reading. Doctors' watches historically favoured the shorter graduations because speed mattered in practice, while modern pulsometers aimed at collectors often use 30.
Crucially, you must use the graduation your dial is actually printed for. Counting 30 beats on a scale calibrated for 15 will give you a reading that is exactly half the truth, which is the single most common mistake with these dials.
A short history of the doctor's watch
Pulsometer chronographs were working instruments. Before electronic monitors, a physician taking a pulse needed a watch with a seconds hand and had to do the arithmetic mentally. A pulsometer removed the arithmetic, which mattered when you were doing it dozens of times a day.
They largely disappeared from catalogues once digital monitors arrived, then returned as a design feature. Modern pulsometers from Longines, Oris and others are worn for the look of the scale rather than for clinical use, and the red pulsometer track has become a recognisable vintage cue.
The related asthmometer scale, calibrated for breaths rather than heartbeats, worked identically and is much rarer. If you find a dial with both, it was almost certainly built for medical work rather than for style.
Common questions
How do you use a pulsometer watch?
Start the chronograph as you begin counting heartbeats. Count up to the number printed on the dial, usually 15, 20 or 30 pulsations, then stop the chronograph. The pulsometer scale where the seconds hand stopped gives you beats per minute directly.
What does 'graduated for 30 pulsations' mean?
It means the scale is calibrated on the assumption that you will count exactly 30 heartbeats. Counting a different number gives a wrong reading, so match your count to whatever the dial says.
Is a pulsometer accurate?
Accurate enough for a rough reading, and it was good enough for clinical use for decades. The error comes almost entirely from human timing rather than the watch, which is why longer graduations give steadier results. It is not a medical device.
What is the difference between a pulsometer and a tachymeter?
Both are pre-solved division scales on a chronograph. A tachymeter converts elapsed time over a known distance into speed, and a pulsometer converts elapsed time over a known number of heartbeats into a rate per minute. The underlying arithmetic is identical.
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