How to use
- 1Enter a distance, unit (metres or yards) and time to get your pace per 100 and speed.
- 2Read projected times for 50 m up to the 3.8 km Ironman swim at that pace.
- 3Enter your 400 and 200 test times to get your critical swim speed and training targets.
- 4For SWOLF, enter lengths, total strokes and total time.
Pace per 100 and projected times
Swim pace is time ÷ distance × 100: 1,500 m in 30:00 is 2:00 per 100 m, or 3.0 km/h. Projected times simply apply that pace to other distances — useful for triathlon (750 m sprint, 1.5 km Olympic, 1.9 km half, 3.8 km full) — but remember you slow down over longer swims. In 25-yard US pools, 100 yd is 91.44 m, so the same effort is roughly 9% faster per 100 yd.
Critical swim speed (CSS)
CSS, based on the critical speed concept (Wakayoshi et al., 1992), approximates your threshold pace: the fastest pace you can hold for around 30 minutes. After a good warm-up swim a 400 all-out, recover, then a 200 all-out. CSS pace per 100 = (T400 − T200) ÷ 2; with 7:20 and 3:30 it is 1:55 per 100 m. Common coaching guidelines use CSS + 6–10 s per 100 for endurance sets, CSS ± 2 s for threshold sets and CSS − 3–5 s for speed work.
SWOLF — swim efficiency
SWOLF (swim + golf) is strokes plus seconds for one length: 18 strokes and 28 seconds is 46. Like golf, lower is better, but compare only with yourself, in the same pool length and at similar effort, since taller swimmers take fewer strokes. If your SWOLF drops while pace stays the same, your technique is getting more efficient.
Frequently asked questions
What is a good swim pace per 100 m?
Beginners often swim 2:30–3:00 per 100 m freestyle, fitness swimmers 1:50–2:15, strong triathletes 1:20–1:40 and elite pool swimmers under 1:00 in a race.
How do I calculate CSS?
Swim a 400 and a 200 at maximum effort with full recovery in between. Subtract the 200 time from the 400 time and divide by 2: (440 s − 210 s) ÷ 2 = 115 s = 1:55 per 100 m.
What is a good SWOLF score?
In a 25 m pool, many recreational swimmers are around 40–50 and experienced swimmers 30–40. It depends heavily on height and pool length, so track your own trend.
How long does it take to swim 1.9 km?
At 2:00 per 100 m about 38 minutes; at 1:45 per 100 m about 33 minutes. Open water usually adds a little for sighting and waves unless you wear a wetsuit.
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