How this instrument works
Total swim time is the total time a swim of a given distance should take at a steady per-100-metre pace: total time = pace per 100 m x (distance ÷ 100). Pace per 100 m is the standard unit swimmers, coaches, and pool clocks use, because competitive pools are built and measured in 25 m (short course) or 50 m (long course) lengths, and 100 m — two or four lengths — is the natural base unit for describing swim speed.
The calculation scales a known pace straight up to any distance: a swimmer holding 2:00 per 100 m needs 30:00 to cover 1500 m, the 'Olympic distance' triathlon swim leg, or 15:00 to cover a 750 m sprint-distance swim leg at the same pace. It assumes the pace holds perfectly steady across the whole distance, which is a reasonable planning assumption for a controlled pool set but less realistic in open water, where drafting, sighting, currents, and wetsuit buoyancy all shift the real time from the flat-pool number.
Swimmers use this both ways: forward, to turn a known pace into a total time for planning a set or a race, and backward, to check whether a completed swim's total time matches the pace they intended to hold. Coaches building a workout often specify a set in exactly this form — '10 x 100 m on 2:00 pace' — where this calculator's total-time output is the number the whole set should add up to.
- Enter Pace (min per 100 m) — your steady swim pace for every 100 metres covered.
- Enter Swim distance (m) — the total distance you're planning or estimating, in metres.
- Read Total swim time (minutes) — the time that pace and distance combination should take.
- For a triathlon swim leg, use the standard event distance: 750 m sprint, 1500 m Olympic/standard, 1900 m half-iron, or 3800 m full iron.
Worked example — 2:00 per 100m over a 1500 m swim
Enter a pace of 2 minutes per 100 m and a distance of 1500 m — the standard Olympic-distance triathlon swim leg. Total time = 2 x (1500 ÷ 100) = 2 x 15 = 30.00 minutes, the swim-leg time to plan around at that pace.
Questions
How do I find my pace per 100 m if I only know my total time for a set?
Divide the total time by the distance in hundreds of metres: pace per 100 m = total time ÷ (distance ÷ 100). A 1000 m set finished in 15:00, for instance, works out to a 1:30 per 100m pace — the reverse of the calculation this page runs forward.
Why is swim pace measured per 100 m instead of per mile or per km, like running?
Because competitive pools are built in 25 m or 50 m lengths, so 100 m — two or four lengths — is the natural, easily-timed unit for a pool swimmer, and pace clocks on deck are set up around round-100 splits. Open-water and triathlon swimming borrow the same per-100m convention even though the swim itself isn't in a lined pool.
Does this account for open-water conditions like currents or wetsuits?
No — it's a flat calculation assuming the entered pace holds steady for the whole distance, with no adjustment for current, chop, drafting behind other swimmers, or the extra buoyancy a wetsuit provides. Open-water swims commonly run faster than the equivalent pool pace would predict purely from those effects, so treat the output as a pool-pace baseline rather than a precise open-water forecast.
What's the difference between sprint, Olympic, and Ironman triathlon swim distances?
A sprint-distance triathlon swim leg is 750 m, the Olympic (standard) distance is 1500 m, a half-iron (70.3) swim is 1900 m, and a full Ironman swim is 3800 m — each roughly doubling as the race format gets longer. Entering any of these as the distance, alongside a target or recent pace, gives the swim-leg time to plan the rest of a triathlon pacing strategy around.
Can I use this for a shorter interval instead of a whole swim?
Yes — the formula works at any distance, so it applies equally to a single 100 m rep, a 400 m warm-up, or a 3800 m Ironman swim leg. Enter the pace you're holding, or targeting, and the distance of just that piece, and the total time comes out for that segment alone.