Swimming Pace Calculator

It doesn't in this calculator -- estimated calories burned is based purely on total elapsed time (roughly 500 calories per hour at a moderate effort), not on distance covered. Two swims of the same duration show the same estimated calorie burn here even if one covered noticeably more distance, since the calculator doesn't factor swim intensity or stroke type beyond that single flat hourly rate.

SWOLF combines your stroke count per pool length with your time in seconds for that length, so a lower total means you covered the length using fewer strokes, less time, or some combination of both. Competitive and fitness swimmers track SWOLF over time as an efficiency metric distinct from raw speed -- it's possible to swim a length faster by simply stroking harder and more often, which speed alone won't distinguish from genuinely more efficient technique, but a falling SWOLF score at a similar pace usually does indicate improving efficiency.

Treat it as optimistic. This calculator's race predictions scale your current pace per 100m linearly to the target distance, with no adjustment for the fatigue and pacing changes that come with attempting a much longer swim. Real swim performance typically slows somewhat over greater distances, so a genuine 1500m attempt will likely be slower than a straight linear scale-up of a 400m pace suggests -- the prediction is most reliable when the target distance is close to the distance you actually swam.

No -- Pace per 100m and Speed are both derived purely from total distance and total time, independent of Pool Length. What Pool Length does change is Total Laps and Time per Lap, since a 50m pool requires half as many laps to cover the same distance as a 25m pool, with each lap correspondingly taking about twice as long.