Open Water Swim Pace Calculator

About this calculator

Open water swimming is consistently slower than the same effort in a pool, because swimmers lose the push-off and glide from wall turns every 25 or 50 metres, must sight periodically to navigate without lane lines, and contend with currents, chop and lack of a black line on the bottom to follow — factors that typically add a meaningful percentage to per-100 pace even for strong pool swimmers. Estimating open water pace by simply reusing a pool-pace number tends to produce an overly optimistic finish-time prediction for a triathlon or open water race.

Triathletes and open water racers use this adjustment to convert a known pool pace into a realistic open water pace and total swim leg time, accounting for the specific conditions of the swim (calm lake versus choppy ocean, wetsuit or not) rather than assuming pool-identical performance on race day.

This calculator takes your pool pace and adjusts it for open water conditions to estimate your open water pace and total swim time.