12 free tools
Health & fitness calculators
Understand your body with calculators based on the formulas doctors and dietitians use: body mass index, calories to maintain or lose weight, macronutrients, body fat percentage, ideal weight, water intake, heart rate training zones, sleep cycles, due dates and fertile days.
Each page explains the formula with a worked example. Results are estimates for healthy adults, not medical advice, so speak to a doctor about any health decision.
- Calorie CalculatorHow many calories you need a day to lose, maintain or gain weight.Popular
- BMI CalculatorBody mass index in kg/cm or lb/ft, with your healthy weight range.
- BMR CalculatorYour basal metabolic rate with three equations, plus daily burn by activity.
- Macro CalculatorDaily grams of protein, carbs and fat for fat loss, maintenance or muscle.Popular
- Body Fat CalculatorBody fat percentage from a tape measure, using the US Navy method.
- Ideal Weight CalculatorIdeal weight for your height from four formulas, plus the healthy BMI range.
- Water Intake CalculatorHow much water to drink a day for your weight, exercise and climate.
- Pregnancy Due Date CalculatorDue date, how many weeks pregnant you are, and key milestones.Popular
- Ovulation CalculatorYour fertile window and likely ovulation date for the next few cycles.
- Sleep CalculatorBest times to go to bed or wake up, based on 90-minute sleep cycles.Popular
- Calories Burned CalculatorCalories burned walking, running, cycling, swimming and 25+ activities.
- Heart Rate Zone CalculatorMax heart rate and your five training zones, including Zone 2.
Frequently asked questions
How accurate are these calculators?
They use well-established formulas such as Mifflin-St Jeor for calories and the WHO BMI categories. Results are good estimates, but individual needs vary.
Is my health data stored?
No. Everything you enter stays in your browser.