Calorie Calculator
Enter your sex, age, weight, height and how active you are, and the calculator estimates your basal metabolic rate and the calories you need each day to keep your weight steady. A table then shows the daily calories for losing or gaining 0.25 or 0.5 kg a week. If you know your body fat percentage you can use it for a second equation. Metric and imperial units are supported. Everything runs in your browser.
| Goal | Change a day | Calories a day |
|---|---|---|
| Lose 0.5 kg a week | -550 | 2,209 |
| Lose 0.25 kg a week | -275 | 2,484 |
| Maintain weight | 0 | 2,759 |
| Gain 0.25 kg a week | +275 | 3,034 |
| Gain 0.5 kg a week | +550 | 3,309 |
The basal metabolic rate comes from the Mifflin-St Jeor equation, 10 x kg + 6.25 x cm - 5 x age, plus 5 for men and minus 161 for women. If you enter a body fat percentage the Katch-McArdle equation is used instead, 370 + 21.6 x lean mass in kg. The maintenance calories are the BMR times your activity factor. A kilogram of body fat is taken as about 7,700 kcal, so a loss of 0.5 kg a week means about 550 fewer kcal a day. All of this is an estimate for adults and real needs differ by several hundred kcal from person to person, so use the result as a starting point and adjust it from your own results. It is not medical advice, and it does not suit pregnancy, illness or under-18s. Everything runs in your browser.
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Student ToolsAbout the Calorie Calculator
Your basal metabolic rate, or BMR, is the energy your body uses at rest. The Mifflin-St Jeor equation estimates it as 10 x weight in kg + 6.25 x height in cm - 5 x age, then adds 5 for men or subtracts 161 for women. A 30 year old man of 80 kg and 180 cm has a BMR of 1,780 kcal. Multiplying by an activity factor, from 1.2 for a mostly sedentary day to 1.9 for a very active one, gives total daily energy expenditure, or maintenance calories: 1,780 x 1.55 is about 2,759 kcal for moderate activity. If you enter a body fat percentage, the Katch-McArdle equation is used, 370 + 21.6 x lean body mass in kg. For weight goals the tool uses the common rule of thumb that a kilogram of body fat holds about 7,700 kcal, which means a weekly change of 0.5 kg is about 550 kcal a day. These are population estimates, real needs differ by several hundred kcal between people, and the body adapts as weight changes, so treat the numbers as a starting point and adjust from your own results. The tool flags targets below 1,200 kcal for women or 1,500 kcal for men. It is not medical advice and it does not suit pregnancy, illness or anyone under 18.
How many calories do I need a day?▾
It depends on your size, age, sex and activity. For a 30 year old man of 80 kg and 180 cm with moderate activity the estimate is about 2,759 kcal a day to maintain weight.
What is BMR?▾
Basal metabolic rate is the energy your body burns at rest to keep you alive, such as for breathing and circulation. It is the biggest part of daily energy use for most people.
How many calories make a kilogram of fat?▾
A common rule of thumb is about 7,700 kcal, or 3,500 kcal per pound. It is an approximation, because the body adjusts as weight changes.
Is the Mifflin-St Jeor equation accurate?▾
It is a widely used estimate that is usually within a few hundred kcal for adults, but individuals differ, so check it against your real results over a few weeks.
Is my data uploaded?▾
No. The calculation runs in your browser and nothing you enter is sent anywhere.