Useful numbers.
Honest uncertainty.
Every calculator shows its assumptions, gives you a range where a range is more truthful, and tells you what the number cannot know.
RUNNING · INTENSITY
Zone 2 + all heart-rate zones
Use heart-rate reserve by default, see all five zones, and treat age as the fallback when no credible exercise data exists.
Open tool →RUNNING · RACE PLANNING
Half marathon time predictor
Compare 5K, 10K or 10-mile equivalents, then add half-specific volume, long-run and pacing evidence.
Open tool →RUNNING · RACE PLANNING
Marathon time predictor
Turn a recent 5K, 10K or half marathon into a theoretical ceiling and a more conservative planning estimate.
Open tool →HYROX · COMPLETE RACE
HYROX race calculator & simulator
Predict a finish time or turn a target into a complete pace budget for eight runs, eight stations and Roxzone.
Open tool →HYROX · FIRST RACE
HYROX readiness check
Assess preparation coverage across running, consistency, station familiarity and time remaining.
Open tool →