Both estimates update as you type and show the formula with your own numbers. Work out roughly how many calories you burn in a day, and estimate your body fat from a tape measure. It is free, private and needs no sign-up.
How to use the calculator
- On the Daily calories tab, choose Metric or Imperial, then Male or Female.
- Enter your age, Height and Weight.
- Pick your Activity level from the list.
- Read your result in kcal a day to maintain weight, with the formula shown using your own numbers.
- Open the Body fat tab, enter your tape measurements and read the estimated body fat.
How the daily calorie estimate works
First the Mifflin-St Jeor equation estimates your basal metabolic rate (BMR), the energy your body uses at complete rest: 10 × weight in kg + 6.25 × height in cm − 5 × age, then + 5 for the male formula or − 161 for the female one. That is multiplied by an activity factor, from 1.2 for little exercise to 1.9 for very hard daily exercise or physical work, to give your total daily energy expenditure (TDEE), the rough number of calories that keeps weight steady.
Choosing an activity level
Be honest and lean towards the lower option. Most people who sit for work and exercise a few times a week fit the light or moderate levels. Choosing too high a level is the most common reason an estimate runs too generous.
How accurate is it?
Mifflin-St Jeor is one of the better formulas for adults, but it is still an average. Many people land within about 10% of a measured value; some are further off, especially very muscular people, older adults and anyone with a medical condition. Picking an activity level is guesswork too, so treat the result as a starting point to compare with how your weight actually changes over a few weeks. It is not meant for children, during pregnancy, or as medical advice.
Using the number
The result is a maintenance figure. Eating less than it over time tends to lose weight, and eating more tends to gain it. Make changes gently, watch your weight over several weeks, and speak to a doctor or dietitian before making big changes, especially if you have a health condition.
The US Navy body fat method
It estimates body fat from height and the circumference of your neck and waist, plus your hips for the female formula. Measure on bare skin with a flexible tape, snug but not pressing in: the neck just below the larynx, the waist at the navel for the male formula or at the narrowest point for the female one, and the hips at their widest. Measure two or three times and use the average. There is no single right number for everyone; reference ranges differ by source, age and sex.
Privacy
Your measurements stay in your browser. Nothing is sent anywhere or stored, apart from your choice of units and tab if you come back.
Questions
What is the difference between BMR and TDEE?
BMR is the energy you use at rest. TDEE adds the energy from moving around and exercising, so it is the figure that matters for day-to-day eating.
Why is my result different from another calculator?
Different calculators use different formulas and activity factors. Choose one and track your own results over time.
Is the body fat result exact?
No. Tape methods are rough estimates and can be several points out. They are best for tracking your own change using the same technique each time.
Is this medical advice?
No. It is an estimate for general information only.