Swimming time converter
A time in one pool as the time it equals in another: 25 m, 50 m and 25-yard pools, by the rules Swimming New Zealand and the NCAA use.
* Swimmers are those who raced at a meet in Swimming New Zealand’s results; club members who did not race are not counted.
What is this time in another pool?
For example, 1:10.06 in a 25 m pool is 1:11.76 in a 50 m pool and 1:02.77 over 100 yards by these rules.
An equal time by a rule, not a prediction: no swimmer’s time moves between pools exactly by it. Swimming New Zealand sets its qualifying times by its rule; the NCAA’s rules book gives its table for US college meets, whose hosts may use their own.
Source: Swimming New Zealand’s qualifying times (NZ Age Group, NZ Open) · the NCAA Swimming and Diving Rules Book 2025-26 and 2026-27, Appendix C
How much slower were New Zealand swimmers in a 50 m pool?
Swimmers who swam the 100 Freestyle in both pools within 45 days in 2026 so far were typically 2.3% slower in the 50 m pool; Swimming New Zealand’s rule makes this time 2.4% slower.
Their typical 25 m time was 1:10.06: the percentage is what these swimmers did, not a rule for every time.
Every event: How much slower is a 50 m pool?
Source: Swimming New Zealand results, 1 Jan to 10 Nov 2026 · n = 1,079
Which rules convert the times?
Between 25 m and 50 m pools, Swimming New Zealand’s rule adds 0.85 s for each 50 m of freestyle, the same for every swimmer; to yards, the NCAA’s rule multiplies a 25 m time by 0.896 for most races, and a 50 m time by a factor of its own for each event and gender.
Swimming New Zealand’s seconds come from its 2026 qualifying times, the same for every age and both genders. The NCAA’s factors are the sample tables of its rules book: the time in seconds times the factor, what is under a hundredth dropped.
Swimming New Zealand: from a 25 m to a 50 m pool
| Stroke | Seconds a 50 m |
|---|---|
| Freestyle | 0.85 s |
| Backstroke | 0.85 s |
| Breaststroke | 1.00 s |
| Butterfly | 0.70 s |
| Individual Medley | 0.85 s |
The NCAA: from a 50 m pool to a 25-yard pool
| Event | Women | Men |
|---|---|---|
| 50 Freestyle | × 0.871 | × 0.86 |
| 100 Freestyle | × 0.874 | × 0.863 |
| 200 Freestyle | × 0.874 | × 0.865 |
| 400 Freestyle (to 500 yards) | × 1.112 | × 1.105 |
| 800 Freestyle (to 1000 yards) | × 1.12 | × 1.105 |
| 1500 Freestyle (to 1650 yards) | × 0.975 | × 0.965 |
| 100 Backstroke | × 0.853 | × 0.835 |
| 200 Backstroke | × 0.857 | × 0.849 |
| 100 Breaststroke | × 0.87 | × 0.856 |
| 200 Breaststroke | × 0.878 | × 0.858 |
| 100 Butterfly | × 0.877 | × 0.868 |
| 200 Butterfly | × 0.881 | × 0.866 |
| 200 Individual Medley | × 0.867 | × 0.857 |
| 400 Individual Medley | × 0.876 | × 0.865 |
From a 25 m pool to a 25-yard pool the NCAA’s factor is the same for women and men: × 0.896, but × 1.143 from the 400 and 800 m freestyle to 500 and 1000 yards and × 1.003 from the 1500 m freestyle to 1650 yards. The rules book says championships may use their own: for selection to its 2027 Division I championships the NCAA takes 25 m times × 0.906 (1.153, 1.013), and for Division I and II only 25-yard and 25 m times count. Its table has no factor from a 50 m pool for the 50 backstroke, breaststroke and butterfly: this page converts those through their 25 m time.
Source: Swimming New Zealand’s 2026 qualifying times · the NCAA Swimming and Diving Rules Book 2025-26 and 2026-27, Appendix C · NCAA, 2027 Division I qualifying standards (updated 15 June 2026)