Zone 2 heart rate calculator
Compare Zone 2 methods and see all five estimated heart rate training zones.
Century Tools
Free calculators to help you understand your health, sleep, recovery and training.
Chronotype calculator
Use your usual sleep times to estimate your sleep midpoint, corrected for catch-up sleep on free days.
Race time predictor
Use two recent races to estimate how your pace changes with distance, then project another race.
Adaptive TDEE calculator
Estimate recent energy expenditure from your own intake and weight trend instead of an activity multiplier.
Personal hydration planner
Turn a sweat-rate test into a planning range for a similar session, without a one-size-fits-all drinking rule.
VDOT training pace calculator
Use a completed race to estimate performance-based running fitness and example training speeds.
Circadian sleep timing analyzer
See whether your sleep timing stays steady across a week, even when some nights cross midnight.
Training load timeline
Turn manually logged training time and perceived effort into a transparent seven-day load pattern.
Sweat rate test analyzer
Use a simple before-and-after field test to estimate how much fluid you lost in that session.
Wrist temperature baseline analyzer
Put one wrist-temperature change in the context of several nights from the same device.
