Swim Pace Calculator
Enter a distance and a time to get your pace per 100 metres and per 100 yards side by side, plus average speed and how many lengths that is in your pool.
Time taken
Swim pace is your total time divided by the distance, expressed per 100 — and because one yard is 0.9144 m exactly, a pace per 100 yards is always about 8.56% lower than the same swimming measured per 100 metres.
100 yards is not 100 metres
This is the mistake worth getting out of the way first, because it makes swimmers think they have got faster or slower when nothing has changed. Most pools in the United States are short course yards. Almost everywhere else, and every international competition, is metric. The two are quietly different lengths.
| Same swim, 1000 m in 20:00 | Reads as |
|---|---|
| Pace per 100 metres | 2:00.0 |
| Pace per 100 yards | 1:49.7 |
| Difference | 10.3 seconds — entirely the unit, not the effort |
Ten seconds per hundred is a large margin in swimming. It is the difference between two training bands. So when a plan prescribes “1:45 per 100”, the first question is always per 100 what.
How to calculate swim pace
There is no model here and nothing is estimated — it is one division:
pace per 100 = total time ÷ (distance ÷ 100)
For 1000 m in 20 minutes: 1200 seconds ÷ 10 hundreds = 120 seconds, or 2:00 per 100 m. To get the same swim in yards, convert the distance first — 1000 ÷ 0.9144 = 1093.6 yards — then divide again: 1200 ÷ 10.936 = 109.7 seconds, or 1:49.7.
Going the other way, multiply a 100 yd pace by 1.0936 to get the equivalent per 100 m. A tidy 1:30 per 100 yd is about 1:38.4 per 100 m.
Counting lengths
A 25 m pool gives 40 lengths per kilometre, and a 50 m pool gives 20. A 25 yard pool is 22.86 m, so a kilometre there is about 43.7 lengths — not a round number, which is exactly the tell that the distance and the pool are in different units. If the lap count above comes out fractional, that is usually why.
What this calculator will not tell you
It will not tell you whether your pace is good. That depends on stroke, distance, age and training history, and a single number covering all of those would be worthless. It also does not convert performance between pool types: a short-course swim includes more turns and push-offs than the same distance long course, and turns are usually faster than swimming. The conversion above is arithmetic on the units, nothing more.
If you want the effort side rather than the distance side, the target heart rate calculator shows training zones, and the calories burned calculator covers swimming as an activity. For running rather than swimming, the running pace calculator does the same job per kilometre and mile.
Swimming counts toward the weekly aerobic activity recommended for adults by both the NHS and the US Physical Activity Guidelines. This page is general information, not medical advice.
Frequently asked questions
How do I calculate swim pace?
Divide your total time by the distance, then express it per 100. A 1000 m swim in 20 minutes is 1200 seconds over 10 hundreds, which is 2:00 per 100 m. Enter any distance and time above and this calculator returns pace per 100 metres and per 100 yards at the same time.
Is 100 yards the same as 100 metres in swimming?
No, and this is the single most common mix-up in swim pacing. One international yard is 0.9144 metres exactly, so 100 yards is 91.44 metres — about 8.56% shorter. The same swimming that produces 2:00 per 100 m produces 1:49.7 per 100 yd. That is not a faster swim, just a shorter unit.
What is a good swim pace per 100m?
There is no universal figure, and anyone quoting one is guessing. Pace depends heavily on stroke, distance, and experience — a sprinter and a distance swimmer are not doing the same task. A more useful approach is to record your own pace over 400 m or 1000 m and watch whether it trends downward over months. This calculator makes no judgement about whether a pace is good.
How do I convert a 100 yard time to a 100 metre time?
Divide the yard distance by 0.9144 to get metres, or multiply a 100 yd pace by 1.0936 to get the equivalent 100 m pace. A 1:30 per 100 yd works out at roughly 1:38.4 per 100 m. Note this is a pure unit conversion, not a performance conversion — it does not account for the extra turns in a shorter pool.
Why is my distance not a whole number of lengths?
Almost always because the distance and the pool are in different units. 1000 metres is exactly 40 lengths of a 25 m pool, but in a 25 yard pool it is about 43.7 lengths, because 25 yards is only 22.86 m. If the lap count above comes out fractional, check which unit your pool is actually measured in.
Sources
- NIST Special Publication 811, Appendix B.9 — Conversion Factors — International yard = 0.9144 m exactly, so 100 yd = 91.44 m
- ODPHP/HHS — Physical Activity Guidelines for Americans (2nd ed.) — Swimming counts toward weekly aerobic activity
- NHS — Physical activity guidelines for adults aged 19 to 64 — Swimming listed as a moderate-intensity aerobic activity
The thresholds and formulas used by this calculator follow the primary sources above. This tool provides general information, not personalised medical advice.