Predict swim times from VO2max + Cost of Transport. Includes environment modifiers (pool 25 yd / 25 m / 50 m, open water fresh / salt, wetsuit), drafting, chop, sighting, and VO2 kinetics for short swims (≤ 400 m). Calibration mode back-solves Cr from a known race time.
Cr (cost of transport) tier-presets: elite 0.55 · trained 0.70 · recreational 0.90 · poor 1.10 ml O2/kg/m. Or back-solve Cr from a real swim time using the calibration block.
If you have a recent honest swim time, we’ll work backward to find your Cr. That gets pushed into the main calculator.
Same shape as the cycling and run versions; swim-specific modifiers.
v (m/s) = (VO2/60) × fraction / Cr_eff
Cr is liters O2 per kg per meter, swim is 4–8× more expensive than running for the same metabolic rate.
Cr_eff = Cr × env × draft × chop × sight
Wetsuit reduces Cr ≈ 8% (more buoyancy, less drag). Drafting in OW saves ~3–8%. Chop & sighting cost time.
For ≤ 400 m, the iterative on-kinetics adjustment uses τ = 25 s (default). Mean VO2 over the effort is reduced by the slow ramp; matters most at 50–200 m.
Cr varies enormously between swimmers, 0.55 for an Olympic-level swimmer, 1.10+ for adult-onset triathletes. Same VO2max, the elite swimmer goes 2× as fast at the same metabolic rate. That’s why technique matters more than fitness for swim improvement.
Run the calibrator with your honest 400 m TT time to get your true Cr. Then use the main calculator to project race times under different conditions (wetsuit vs not, drafting vs not, calm vs choppy).
Yousuli’s swim protocol uses Slipstream stationary-swim setup with EO SwimBETTER force pads, measures VO2max and stroke economy together. The calibrated Cr you walk out with makes this calculator’s predictions race-grade.
Spotted a bug? Email info@yousuli.co.
