# Free fitness and health calculators

- [TDEE calculator](https://revns.com/tools/tdee-calculator.md): Free TDEE calculator. Estimate your resting and total daily energy expenditure with the Mifflin-St Jeor equation, then see calorie targets to lose, keep or gain weight.
- [Protein calculator](https://revns.com/tools/protein-calculator.md): How much protein do you need? Get a daily range in grams from your weight and goal, split per meal, with vegetarian, vegan and non-vegetarian food examples.
- [One-rep max calculator](https://revns.com/tools/one-rep-max-calculator.md): Estimate your one-rep max from any set of 1 to 12 reps with the Epley and Brzycki formulas, and get a percentage table for planning sets.
- [Running pace calculator](https://revns.com/tools/running-pace-calculator.md): Work out running pace per kilometre or mile from distance and time, and predicted finish times for 5K, 10K, half marathon and marathon at that pace.
- [Heart rate zone calculator](https://revns.com/tools/heart-rate-zone-calculator.md): Calculate your five heart rate training zones from maximum heart rate (Tanaka formula) and, if you know it, resting heart rate with the Karvonen method.
- [BMI calculator](https://revns.com/tools/bmi-calculator.md): Calculate body mass index from height and weight, see the WHO adult categories, and learn why waist and trends matter more for active people.
- [Sleep calculator](https://revns.com/tools/sleep-calculator.md): Find bedtimes that give you full 90-minute sleep cycles before your alarm, and check them against the 7 to 9 hours adults are advised to sleep.
- [Water intake calculator](https://revns.com/tools/water-intake-calculator.md): A practical daily water target from body weight and training time, compared with the reference total water intakes for adults.
- [Bristol stool chart](https://revns.com/tools/bristol-stool-chart.md): What the Bristol stool scale types 1 to 7 describe, what is usual, and which changes are worth talking to a doctor about. Pick a type to see it explained.
- [VO2 max calculator](https://revns.com/tools/vo2-max-calculator.md): Estimate VO2 max three ways: the Cooper 12-minute run, a 1.5-mile run time, or the ratio of maximum to resting heart rate. See what the number means and how to raise it.

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Canonical: https://revns.com/tools
Index of everything: https://revns.com/llms.txt
revns gives training guidance, not medical advice.