Triathlon Race Time Predictor
Enter the thresholds you already train with — FTP, run threshold pace, swim CSS — and get a realistic finish time with swim, bike, and run splits, target power and pace for each leg, and the race's total training stress.
Race type
Predicted finish
5:13:00
327 total TSS
Target pace 1:57/100m
39 TSS
180W (75% FTP) · ~33 km/h
154 TSS
Target pace 5:18/km
134 TSS
How to use it
- 1Pick your race: sprint, Olympic, 70.3, or Ironman — or a standalone 5K, 10K, half, or marathon.
- 2Enter your FTP (watts) and body weight for the bike leg.
- 3Enter your run threshold pace (your roughly one-hour race pace per km).
- 4Enter your swim CSS (critical swim speed) per 100 m — use the CSS calculator if you don't know it.
- 5Read your predicted finish, per-leg splits, and target power/pace for race day.
Not another flat finish-time formula
Most predictors apply one Riegel exponent to a single input and call it a day. This one models each discipline the way it actually behaves: the bike leg solves the aerodynamic drag and rolling-resistance equation for the speed your race power produces, the swim adds distance degradation plus an open-water penalty, and the run stacks a distance factor with a triathlon run-off fatigue multiplier — because a 70.3 half-marathon off the bike is nothing like an open half-marathon.
It's the same engine that builds your plan
This is the exact predictor PaceBeats runs internally to seed the training stress of each race leg when it generates a season. So the splits you see here are a faithful preview of how the coaching engine reasons about your race — not a throwaway marketing widget bolted on the side.
Works with whatever thresholds you have
Know your FTP but not your swim CSS? Enter what you have. The predictor returns a confident estimate for the legs it can model and falls back to distance-typical values for the rest, then flags the result as predicted, partial, or fallback so you always know how much to trust it.
How the math works
Bike speed is found by Newton's method on k·v³ + Crr·w·v = race power, with race power set as a distance-specific fraction of FTP (Coggan intensity guidelines: ~92% for a sprint down to ~68% for an Ironman). Swim pace applies a distance degradation factor to your CSS plus a 1.06 open-water adjustment. Run pace applies a Daniels/Riegel distance factor to your threshold pace, then a triathlon fatigue multiplier (up to ~1.18 for an Ironman marathon). TSS for each leg uses the same power/pace/CSS formulas the app scores real activities with. Estimates assume a flat-to-rolling course in fair conditions; hilly courses, heat, and chop will run slower.
Built and reviewed by the PaceBeats coaching-engine team. Every calculator runs the same sports-science math that powers the app's adaptive plans.
Common questions
How accurate is the triathlon time predictor?
On a flat-to-rolling course in fair conditions it is typically within a few percent for athletes who enter accurate thresholds. It does not yet model course elevation, wind, heat, or your pacing discipline, so treat it as a well-grounded target rather than a guarantee — and trust it most when all three thresholds are entered (it labels the result predicted, partial, or fallback).
What's the difference between this and a Riegel calculator?
A Riegel calculator extrapolates one known time to another distance with a fixed exponent. This predictor models each discipline from your physiological thresholds and the physics of cycling, then adds the triathlon-specific run-off fatigue a single-sport formula can't capture.
Next step
Turn these numbers into an adaptive plan.
PaceBeats uses this exact math — and your training history — to build and adapt your swim, bike, run, and strength week after week.