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Free health & fitness calculators

Simple, private calculators for weight, nutrition, fitness and pregnancy. Every result comes with a plain-English explanation of how it was worked out and what it means.

BMI Calculator

Check your body mass index and the weight range that is healthy for your height.

Calorie Calculator

Work out your maintenance calories and how much to eat to lose or gain weight.

Macro Calculator

Turn a calorie target into daily grams of protein, carbs and fat.

Body Fat Calculator

Estimate your body fat percentage from a tape measure using the U.S. Navy method.

Ideal Weight Calculator

See your ideal weight using four classic formulas, alongside your healthy BMI range.

Water Intake Calculator

Estimate how much water you should drink each day based on weight, exercise and climate.

Pregnancy Due Date Calculator

Estimate your due date from the first day of your last period, with key pregnancy milestones.

Heart Rate Zones Calculator

Find your maximum heart rate and target heart rate zones for training.

How these calculators work

Each tool uses a published, widely used formula, such as the Mifflin-St Jeor equation for calorie needs or the U.S. Navy method for body fat. Every page explains the formula, its limits, and how to interpret your result.

Everything is calculated in your browser. The numbers you type in are not sent to our servers or stored.

Please read

These tools give estimates for healthy adults. They cannot diagnose or treat any condition. For personal medical advice, talk to a qualified healthcare professional.