Calorie calculator: BMR and TDEE

Estimate how much energy your body uses in a day

This calorie calculator gives two numbers. The first is your basal metabolic rate (BMR): the energy your body uses at complete rest to breathe, keep your heart beating, hold its temperature and maintain its organs. The second is your total daily energy expenditure (TDEE), which adds everyday movement and exercise on top of that base. Both are shown in kilocalories (kcal) and kilojoules (kJ), with the full working.

How to use it

1. Under "Units", keep "Imperial (lb, ft, in)" or switch to "Metric (kg, cm)".
2. Pick "Male" or "Female", then fill in "Age (years)", "Weight (lb)" and your height in "Height: feet (ft)" and "and inches (in)".
3. Under "Formula", keep "Mifflin-St Jeor (default)" or choose "Revised Harris-Benedict".
4. Under "Activity level", select the line that best matches a typical week.
5. Read "Basal metabolic rate (BMR, at rest)" and "Estimated total daily energy expenditure (TDEE)".

To find your values next time, tick "Remember my entry on this device". Without it, nothing is saved.

The formulas, with a worked example

The Mifflin-St Jeor equation, published in 1990, is the default: comparison studies generally find it closer to measured values than older equations. It uses metric units, so pounds and inches are converted first (1 lb = 0.45359237 kg, 1 in = 2.54 cm).

• Male: 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5
• Female: 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161

The Harris-Benedict equation dates from 1919 and was revised in 1984 with new data:

• Male: 88.362 + 13.397 × weight + 4.799 × height − 5.677 × age
• Female: 447.593 + 9.247 × weight + 3.098 × height − 4.330 × age

Example: a 30-year-old man who weighs 176 lb and stands 5 ft 11 in. That is 79.832 kg and 71 in, or 180.34 cm. With Mifflin-St Jeor: 10 × 79.832 + 6.25 × 180.34 − 5 × 30 + 5 = 1,780.45, so a BMR of 1,780 kcal a day (7,449 kJ). The revised Harris-Benedict equation gives 1,853 kcal. For a 25-year-old woman at 132 lb and 5 ft 5 in, Mifflin-St Jeor gives 1,345 kcal and Harris-Benedict 1,404 kcal.

The five activity levels

TDEE = BMR × activity factor. For the man above:

Someone with an office job who drives to work is "Sedentary", even with a walk at the weekend. A nurse on their feet all shift, or someone who cycles three evenings a week, is closer to "Moderately active". If unsure, pick the lower level.

What the estimate cannot tell you

• It is a statistical average: the equations describe groups of people. For one person, the gap with a measured value can be more than 10%.
• Body composition: at the same weight, muscle uses more energy than fat, and the equations cannot see the difference.
• Genetics and age play a part, as do sleep and climate.
• Health: a thyroid condition, medication, illness or recovery all change energy needs.

The calculator is not suitable for people under 18, during pregnancy or breastfeeding, or if you have a medical condition. For any weight or nutrition goal, a doctor or a registered dietitian can take your real situation into account.

Calories, kcal and kJ

One kilocalorie equals 4.184 kilojoules. The "Calories" on a US Nutrition Facts label are kilocalories. Labels in the UK and the European Union show both units, for example "1,046 kJ / 250 kcal", and in Australia kilojoules come first. This tool shows both too: 2,759.69 kcal × 4.184 ≈ 11,547 kJ.

Frequently asked questions

What is the difference between BMR and TDEE?

BMR is what you burn at complete rest. TDEE adds daily activity: it is your BMR multiplied by a factor between 1.2 and 1.9.

Which formula should I choose?

Mifflin-St Jeor, the default, is the most widely used today. Revised Harris-Benedict often gives a slightly higher number. Neither replaces a measurement in a clinic.

Why is there no weight-loss target?

Because a number from an equation knows nothing about your health or history. A goal is best set with a doctor or a registered dietitian.

Is my data sent anywhere?

No. The calculation runs in your browser, and nothing is kept unless you tick the box.