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
| Pool | /100m |
|---|---|
| 25 m | 1:30.0 |
| 50 m | 1:31.6 |
| 25 yd | 1:29.7 |
| 23 m | 1:29.7 |
Estimated equivalent pace 1:31.6/100m
How to use it
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 you need to know
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.
Read the related article
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.
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