Swim Pace and Time Calculator

CSS is the pace you could hold for roughly 1,500 m, calculated from a 400 m and a 200 m time trial: distance difference divided by time difference. The calculator uses it as the anchor for every race distance.

Between 3.5% and 9.5% over the same distance in open water, with the largest gain for less experienced swimmers, who benefit most from the added buoyancy. Removing it costs time in T1.

Sighting, chop, currents and the lack of walls cost about 5% compared with pool pace before the wetsuit gain is applied; that is what elite triathletes lost in a calm lake over 1,500 m (López-Belmonte 2024), a sea swim or a crowded start costs more.

Yes. Enter the distance and time of a recent race, say whether it was in a pool or open water and whether you wore a wetsuit, and the calculator removes those effects and the distance factor to work back to your CSS. Every other distance is then predicted from that.

1,500 m is swum at 100% of CSS. Shorter races are faster, about 3% for 750 m, and longer ones slow down along a logarithmic curve whose steepness depends on swimmer level: experienced swimmers hold their pace over 5 and 10 km far better than newer ones.

Between 10 and 50 seconds depending on swimmer level, shown when you switch on the T1 view. Over a 1.9 km swim the wetsuit still saves several minutes net; over a 400 m sprint swim the balance is close.

Yes. In imperial mode the distances are shown in yards and miles and CSS as pace per 100 yards; the calculation itself is done in metres.

Yes. Under the predictions, pick the distance and the conditions (pool, open water, wetsuit) and press "Take into race plan": the swim split goes into the triathlon planner, which shows where it came from, and the nutrition plan can take it from there.