BMR & Calorie Calculator

The formula (Mifflin-St Jeor)

Men: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5.

Women: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161.

Total Daily Energy Expenditure (TDEE) is then BMR × an activity multiplier, giving a rough estimate of calories needed to maintain your current weight.

Worked example

A 30-year-old man weighing 70 kg at 175 cm has a BMR of 10×70 + 6.25×175 − 5×30 + 5 = 1,648.75 calories/day. With moderate activity (×1.55), his estimated maintenance calories are about 2,556/day.

Method and sources

The equation is Mifflin–St Jeor (Mifflin et al., American Journal of Clinical Nutrition, 1990), which was fitted to measured resting energy expenditure in healthy adults. The activity multipliers (1.2 to 1.9) are the conventional TDEE factors — rough averages, not measurements of you — so treat the result as a starting estimate. The worked example was recalculated independently in September 2026.

Another example

A 40-year-old woman weighing 65 kg at 165 cm: BMR = 10×65 + 6.25×165 − 5×40 − 161 = 1,320.25, which the calculator shows as 1,320 calories a day. With light exercise (×1.375) her estimated maintenance is 1,815 calories. For the 30-year-old man above, choosing sedentary (×1.2) instead of moderate gives 1,979 calories a day.

The five activity levels

• 1.2: sedentary, little or no exercise.
• 1.375: light exercise one to three days a week.
• 1.55: moderate exercise three to five days a week.
• 1.725: heavy exercise six or seven days a week.
• 1.9: a very physical job or very heavy training.

Using and not over-reading the result

Fields use kilograms and centimeters; to convert, 1 lb is about 0.4536 kg and 1 inch is 2.54 cm. The equation was fitted to healthy adults, so it can be off for very muscular people, children, or anyone pregnant or with a medical condition. Most people pick the activity level that matches an honest average week, then adjust after a few weeks of watching their weight.

More examples and limits

A 25-year-old woman who is 170 cm tall and weighs 60 kg has a BMR of 1,377 calories a day; with moderate exercise (1.55) her estimated total is 2,134, and at the highest level (1.9) it is 2,615. A 50-year-old man at 90 kg and 185 cm has a BMR of 1,811, which gives 2,174 when sedentary (1.2) and 3,124 with heavy exercise (1.725). In this formula each extra year of age lowers the BMR by 5 calories.

An age, weight or height of zero or less returns "Please enter positive values." No upper limit is applied, so a height typed in the wrong unit is calculated without complaint; check the entry if a result looks far too high.