Swimmers track pace per 100 metres or yards to set interval sets (“10 × 100 on 2:00”) and race goals. Knowing your lap time helps you pace in the pool.
How to use the Swim Pace Calculator
- Swim distance
- Swim time, hours
- minutes
- seconds
- Pool length
- Distance to predict
- Fatigue exponent (1 = even pace)
Results update as you type, every field has its own unit menu, and everything is calculated in your browser.
How it works
Enter the distance and time, your pool length, a distance to predict and the fatigue exponent.
Tips
- Check local conditions and safety rules before going out.
- Start with conservative equipment choices and adjust with experience.
- Every field has its own unit menu.
- Everything is calculated in your browser.
Common mistakes to avoid
- Using estimates instead of a proper check in the water.
- Mixing feet and metres, or knots and km/h.
- Overestimating your skill in strong wind.
Inputs explained
| Field | What to enter |
|---|---|
| Swim distance | Units: m, yd |
| Swim time, hours | A number |
| minutes | A number |
| seconds | A number |
| Pool length | Choose one: 25 m, 50 m, 25 yd, 33⅓ m |
| Distance to predict | Units: m, yd |
| Fatigue exponent (1 = even pace) | A number |
What each result means
- Pace per 100 m = ([Swim time, hours]×3600 + [minutes]×60 + [seconds])÷[Swim distance]×100÷60
- Pace per 100 yd = ([Swim time, hours]×3600 + [minutes]×60 + [seconds])÷[Swim distance]×91.44÷60
- Speed = [Swim distance]÷([Swim time, hours]×3600 + [minutes]×60 + [seconds])
- Time per pool length = ([Swim time, hours]×3600 + [minutes]×60 + [seconds])÷[Swim distance]×[Pool length]
- Lengths swum = [Swim distance]÷[Pool length]
- Predicted time for the new distance = ([Swim time, hours]×3600 + [minutes]×60 + [seconds])×([Distance to predict]÷[Swim distance])^[Fatigue exponent (1 = even pace)]
Formula
Pace per 100 = time ÷ distance × 100 · Predicted time = time × (new distance ÷ distance)^e (e = 1 for even pace, ≈ 1.03–1.06 for fatigue)
Worked example
Inputs: Swim distance: 1,500 m; Swim time – hours: 0; minutes: 30; seconds: 0; Pool length: 25 m; Distance to predict: 400 m; Fatigue exponent (1 = even pace): 1.
Results: Pace per 100 m = 2:00; Pace per 100 yd = 1:50; Speed = 0.8333 m/s; Time per pool length = 30 s; Lengths swum = 60; Predicted time for the new distance = 8:00.
Key terms
- Pace per 100
- Time to swim 100 m or yd.
Frequently asked questions
What is a good 100 m pace?
Fitness swimmers often swim 1:45–2:15 per 100 m; triathletes 1:30–2:00.
How do I convert yards to metres?
100 yd = 91.44 m.
Is pace constant across distances?
Usually slower over longer swims, so use an exponent above 1.
What is CSS?
Critical swim speed, a threshold pace from 400 m and 200 m times.