Free online sport & fitness calculators
Ten instant sport and fitness calculators that run entirely in your browser. No signup, no upload, no ads.
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Running Pace Calculator
Convert between pace (min/km) and speed (km/h), and calculate total run time from distance and time.
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Marathon Time Predictor
Predict your marathon or half-marathon finish time from a recent race result using Riegel's formula.
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Swim Pace Calculator
Calculate swim pace per 100 m, total session time, and distance from any combination of inputs.
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Cycling Power Estimator
Estimate watts needed to hold a given speed at your weight and road gradient.
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One-Rep Max Calculator
Estimate your one-rep max for any lift using the Epley, Brzycki, and Lombardi formulas.
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Training Load Calculator
Calculate session RPE training load (duration × RPE) to track weekly stress and recovery balance.
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VO₂ Max Estimator
Estimate your VO₂ max from resting and maximum heart rate — no lab or field test required.
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Gym Rest Timer
Countdown timer for rest periods between sets — audio alert when time is up.
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Workout Builder
Build and print a workout plan: add exercises with sets, reps, and rest targets.
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Sleep vs Recovery Score
Score your recovery readiness based on sleep hours and the prior session training load.
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Why use browser-based sport calculators?
Every calculator here runs entirely inside your browser — no server round trips, no account needed. Results are instant and your personal training data never leaves your device. From pace and power to recovery scoring, these tools cover the most common calculations for runners, cyclists, swimmers, and gym-goers.