A tachymeter chronograph is a stopwatch fitted with a scale that turns elapsed time over a known distance into average speed. The scale once lived on the dial flange, but Omega moved it onto the bezel with the 1957 Speedmaster, a decision by designer Claude Baillod marketed as the 'Tacho-Productometer,' which freed up the dial and sharpened legibility. The method is simple: start the chronograph as your subject crosses the start line, stop it one mile or one kilometer later, and the seconds hand points to your speed. Cover the distance in 45 seconds and the hand lands on 80, meaning 80 units per hour. The one catch is that a standard tachymeter only works for events under 60 seconds.
Real examples span the whole price ladder. The Omega Speedmaster Moonwatch Professional, with the hand-wound Calibre 3861 (Co-Axial Master Chronometer, METAS certified) and an anodized aluminum tachymeter bezel, retails around $7,800 for the Hesalite version, and the current model brings back the vintage 'dot over 90' detail. The Rolex Cosmograph Daytona ref. 126500LN pairs a 40mm steel case with a ceramic Cerachrom tachymeter bezel; it lists near $16,000 but trades north of $30,000 on the secondary market. Lower down, the TAG Heuer Carrera with Calibre 16 or Heuer 02 sits between $4,000 and $6,000, the Zenith Chronomaster El Primero 1969 runs about 6,500 euros, and the Hamilton Intra-Matic Auto Chrono lands near $2,000.
When buying, start with where the scale sits. A bezel tachymeter like the Speedmaster or Daytona reads cleanly but dominates the watch's look, while a dial-flange version stays more dressy and discreet. Be honest about whether you will ever actually time anything; for most owners this scale is a piece of motorsport visual code rather than a working tool, and that is fine. On the secondary market, check that the bezel insert is original and not faded or swapped, confirm the numerals line up, and feel the crispness of the pusher action. On vintage Speedmasters, bezel variants matter for dating.
One useful nuance: because a flat tachymeter cannot handle events over 60 seconds, some brands print a spiral or 'snail' tachymeter on the dial to read longer durations, an approach you will see on certain cycling-themed chronographs. Which version suits you comes down to whether you prioritize racing-era looks or genuine measuring range.