Triathlon Pacing Calculator

This calculator works from the finish line backward: it takes your target total time and your known (or estimated) swim pace, subtracts a swim split computed directly from that pace and the race's official swim distance, then subtracts fixed transition times — 90 seconds for T1 and 60 for T2 at sprint/Olympic distance, stretching to 150 and 90 seconds respectively for the longer 70.3 and Ironman distances, since bigger transition areas and more gear changes take longer at those distances. Whatever time remains is split between bike and run using a fixed 53/47 ratio, reflecting the fact that the bike leg is typically the longest single segment of a triathlon and tends to consume slightly more than half of combined bike-and-run time.

Your bike-effort percentage input then adjusts that baseline bike speed up or down — riding above 100% effort produces a faster bike split, but because total time is fixed, the run split is recalculated afterward from whatever time is left over, so an aggressive bike effort can mean a slower forecasted run to hit the same overall finish time. This models one common pacing strategy, not physiology: it doesn't account for how bike intensity actually affects run performance (the real-world "bike-to-run transition cost"), so use the output as a planning target for splits rather than a guarantee that riding harder won't cost you more on the run than the numbers suggest.