Health calculators

A growing library of free, science-backed calculators. Every tool runs in your browser — your data never leaves your device.

Estimate your Body Mass Index — a quick screening tool for whether your weight is in a healthy range for your height.

Work out how many calories you need each day to maintain, lose, or gain weight using the Mifflin-St Jeor equation.

Estimate the total calories your body burns each day from resting metabolism plus daily activity.

Estimate the calories your body needs at complete rest to keep basic functions running.

Estimate a healthy weight range for your height using several validated clinical formulas.

Estimate your body fat percentage using the U.S. Navy circumference method.

Estimate the weight of everything in your body that isn't fat — muscle, bone, organs, and water.

Calculate the ratio of your waist to your hips — a useful indicator of where you carry fat.

Estimate how many grams of protein you need each day based on your weight and activity level.

Split your daily calorie target across protein, carbohydrates, and fat using sensible ratios.

Estimate how much water to drink each day based on your body weight and activity level.

Find the best times to fall asleep or wake up by aligning with 90-minute sleep cycles.

Pick a wake time and we'll work backwards through 90-minute cycles to suggest bedtimes.

Calculate your maximum heart rate and the five training zones using the Karvonen method.

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