Swim Course Converter
Estimate equivalent pace/100 m between pools of different lengths, accounting for the different number of turns, stroke and assumed gain from each wall push-off.
1:30/100m · 25 m → 50 m · +1.6s
- Change
- +1.6s
- Wall
- 0.8s/turn
Estimated equivalent pace 1:31.6/100m
Pace per 100 m in standard pools
| Pool | /100m |
|---|---|
| 25 m | 1:30.0 |
| 50 m | 1:31.6 |
| 25 yd | 1:29.7 |
| 23 m | 1:29.7 |
How it works
Select the length of the pool you swam in and the pool you want to swim in, such as 25 m → 50 m. Enter pace/100 m, stroke and the profile that best represents you. The calculator estimates the pace change caused by the different number of turns.
What to keep in mind
This is a training estimate based mainly on empirical evidence, not an official race-time conversion. The actual difference depends on turn technique, underwater phase, push-off, distance and stroke. An average difference of about 2% between 25 m and 50 m pools has been documented for freestyle in large groups of competitive swimmers, but it is not an individual conversion factor and does not validate assumptions for every stroke.
Methodology & sources
Calculation: time difference = difference in turns per 100 m × assumed gain per turn. Club profile assumptions are Freestyle 0.8 s, Backstroke 0.6 s, Breaststroke 1.0 s, Butterfly 0.7 s and Individual Medley 0.8 s. Recreational applies 0.5× and Elite 1.5×. These are calculator parameters, not official swimming-governing-body factors. As an external magnitude check, Wolfrum et al. found freestyle race performances averaged approximately 2.0 ± 0.6% faster in 25 m pools than in 50 m pools. The study does not provide individual conversions or substantiate other strokes. Converted times are not official race times.
Last updated: 26 June 2026
The pool may change. Your ability in the water does not.
Turns can mask or amplify the numbers on your watch. Through 1:1 coaching, we can assess your actual swim pace and apply it appropriately to your pool and open water.