Fitness Calculators

Choose the right calculator

Estimate pace, heart-rate zones, and fitness measures from the values you enter.

Marathon Pace Calculator

Calculate pace, average speed, projected race time, and checkpoint times for a 42.195 km marathon with even or varied half-race pacing.

Heart Rate Zone Calculator

Compare heart-rate zones from percentages of maximum heart rate and the Karvonen heart-rate-reserve method. These are estimates, not a personalized exercise prescription.

Vo2 Max Calculator

Estimate VO₂ max indirectly using the Cooper 12-minute run or Rockport 1-mile walk protocol. The result is not a laboratory measurement.

Race Time Predictor

Predict race time or calculate pace and speed from a distance and elapsed time. Enter a race distance in miles or kilometers; pace and speed input modes retain their explicitly labeled metric units.

Half Marathon Pace Calculator

Calculate pace, projected finish time, and checkpoints for the official 21.0975 km half marathon. This is approximately 13.1094 miles; “13.1 miles” is a rounded description.

Steps To Miles Calculator

Convert steps to miles and kilometers using a measured stride length or a known-distance calibration. Optional calories are a walking MET estimate, not a clinical measurement.

Bike Size Calculator

Find an indicative adult bike-frame size from height, inseam, and bike type. Manufacturer charts are model-specific; a suggested size does not guarantee fit.

One Rep Max Calculator

Compare Epley and Brzycki one-rep-max estimates from a weight in pounds or kilograms and 1–12 repetitions. The estimates are not recommended loads to lift.

Calories Burned Calculator

Estimate gross energy use from body weight, duration, and one of five activities at three intensities. The local 2024 Adult Compendium MET values are population averages for ages 19–59; the result is not a direct measurement or an estimate of weight change.