Fitness & Exercise Calculators
Plan your training and track your progress, work out running pace and race times, estimate your one-rep max, find your heart-rate zones, gauge VO2 max and count the calories you burned. Every tool uses a recognised exercise-science formula and runs entirely in your browser.
- Running Pace Calculator Enter any two of pace, time and distance, and get the third, with your pace in both min/km and min/mile, and your speed in km/h and mph.
- Pace Converter (min/km, min/mile, mph, km/h) Convert a pace or speed between min/km, min/mile, km/h and mph, enter one and see all four at once.
- One-Rep Max (1RM) Calculator Enter a weight and the reps you managed to estimate your one-rep max, averaged across three proven formulas, with a percentage table for programming.
- Heart Rate Zone Calculator Enter your age to get your five training heart-rate zones, add a resting heart rate for personalised Karvonen zones based on your heart-rate reserve.
- Race Time Predictor Enter one recent race time and get predicted times, and paces, for 5K, 10K, 15K, half and full marathon, using Riegel's formula.
- VO2 Max Calculator (Cooper Test) Do the Cooper test, run as far as you can in 12 minutes, then enter the distance to estimate your VO2 max and see a fitness rating.
- Calories Burned Calculator Pick an activity, enter your weight and how long you did it, and get an estimate of the calories you burned, using standard MET values.
- Steps to Distance Calculator Turn a step count into distance in kilometres and miles, estimate your stride length from your height, or enter your own.
- Swimming Pace Calculator Enter the distance you swam and your time to get your pace per 100 m and per 100 yd.
- Calorie Deficit Calculator Enter how much weight you want to lose and over how many weeks to get the daily calorie deficit required.
- Navy Body Fat Calculator The US Navy method estimates body fat from a few tape measurements, neck and waist for men, plus hips for women, using your height as a reference.
Frequently asked questions
Are these fitness calculators accurate?
They use established exercise-science formulas, Epley/Brzycki/Lombardi for one-rep max, Tanaka/Karvonen for heart rate, Riegel for race prediction, Cooper for VO2 max, and the ACSM MET equation for calories, each cited on its tool page. Formula estimates are population-based, so treat them as guides, not lab measurements.
Do they work in metric and imperial?
Yes, paces show in both min/km and min/mile, weights toggle between kg and lb, and distances handle km and miles.
Is my data uploaded?
No. Every tool runs entirely in your browser, nothing is sent to a server, and they work offline.
Is this medical advice?
No. These are general fitness tools for training and tracking, not medical advice. Check with a doctor before starting hard exercise or a maximal test if you have any health concerns.