Pace per 100 in swimming
Swimmers measure speed as time per 100, either 100 yards in most US pools or 100 meters in long-course and international pools. It makes sets easy to plan: if you hold 1:40 per 100 yards, a 500 takes 8:20. This calculator gives your pace in both units from any swim, or estimates your critical swim speed from two time trials.
The formulas
- Pace per 100 = time ÷ (distance ÷ 100)
- Yards to meters: 1 yard = 0.9144 m, so a pace per 100 m is about 9.4% slower than the same effort per 100 yd
- Critical swim speed (CSS) = (400 − 200) ÷ (400 time − 200 time), in distance per second
- CSS pace per 100 = 100 ÷ CSS
Worked example: a pool swim
You swim 500 yards in 8 minutes 20 seconds.
- 500 s ÷ 5 = 1:40 per 100 yards.
- That is 1:49 per 100 meters.
- At that pace, 1,500 m takes about 27 minutes 20 seconds.
Worked example: a CSS test
After a warm-up you swim a 400 in 6:40 and, after full recovery, a 200 in 3:05.
- Time difference: 400 s − 185 s = 215 s for 200 yards.
- CSS = 200 ÷ 215 = 0.93 yards per second.
- CSS pace = 1:48 per 100 yards.
CSS is close to the pace you can hold for about 30 minutes. Triathletes and masters swimmers use it to set threshold sets such as 10 × 100 at CSS pace with short rests.
Pace and triathlon swim times
| Pace per 100 m | 1,500 m | 1.9 km (1.2 mi) | 3.8 km (2.4 mi) |
|---|---|---|---|
| 1:30 | 22:30 | 28:30 | 57:00 |
| 1:45 | 26:15 | 33:15 | 1:06:30 |
| 2:00 | 30:00 | 38:00 | 1:16:00 |
| 2:15 | 33:45 | 42:45 | 1:25:30 |
| 2:30 | 37:30 | 47:30 | 1:35:00 |
Tips
- Pool length: a 25-yard pool is the US standard for high school and college, 50 m pools are long course. Turns add speed, so long-course paces are a few seconds slower.
- Open water is usually slower than the pool: no push-offs, sighting, waves and currents. A wetsuit, on the other hand, can make you faster.
- Retest CSS every 4 to 6 weeks to keep your training paces honest.
- Count laps carefully: a lap counter or watch avoids a 50-yard error that throws the pace off by 10%.