Swimming
6 calculators
Swimming calculators built around pace per 100 and the two figures derived from it: critical swim speed and stroke efficiency.
Pool distances differ between 25 m, 50 m and 25-yard courses, so any comparison between times swum in different pools needs a distance conversion before the paces mean anything against each other.
- Swimming Pace Calculator Convert swim distance and time into pace per 100 meters for training and race analysis.
- Critical Swim Speed (CSS) Calculator Estimate your critical swim speed from 400 m and 200 m time-trial data.
- Swim Pace Converter (100m to 100y) Convert swim pace between 100-meter and 100-yard intervals using the standard meter-yard ratio.
- SWOLF Score Calculator Calculate your swimming efficiency by combining stroke count and lap time into one metric.
- Swim Distance Converter Convert swimming distances between meters and yards using the standard international conversion factor.
- Swim Split Calculator Divide swim time and distance into equal splits for even-pace training and race pacing.
Critical swim speed and SWOLF
Critical swim speed is estimated from two timed swims over different distances, commonly 400 m and 200 m. The difference in time divided by the difference in distance gives a speed that approximates the pace sustainable without accumulating fatigue — the swimming analogue of a threshold. Because it comes from a two-point line, the accuracy depends on both swims being genuinely maximal.
SWOLF adds the time for a length to the number of strokes taken in it. A lower score means the same distance was covered with less of both, which is why it works as an efficiency measure rather than a speed one. It is only comparable within a fixed pool length and stroke, since both terms change with each.
Pace per 100 is the common currency the rest converts into. A 1:45 per 100 m swim is 0.95 m/s, which is the unit that lets a swim leg be compared against a bike or run leg in a multisport session.
Common questions
What is critical swim speed?
Critical swim speed estimates the pace a swimmer can hold without accumulating fatigue, derived from two maximal time trials over different distances — commonly 400 m and 200 m. Dividing the difference in distance by the difference in time gives a speed that functions as a threshold reference for setting training paces. The estimate is only as good as the two swims: if either is paced rather than maximal, the resulting line is wrong.
What does a SWOLF score mean?
SWOLF adds the seconds taken for a length to the number of strokes used to cover it, so improving either term lowers the score. It measures efficiency rather than speed: a swimmer can lower SWOLF by gliding more even while swimming slower. Scores are only comparable within the same pool length and the same stroke, because both the time and the stroke count change with each.
How do I compare times swum in different pools?
Convert the distances first. A 25-yard pool is 22.86 m, so a 100-yard swim covers 91.44 m rather than 100 m, and comparing the raw times overstates the yard-pool performance. Turn frequency also differs — a short-course swim includes more push-offs than a long-course swim over the same distance, which affects the time independently of swimming speed. The distance converter handles the first of those; the second is a caveat on any comparison.