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BMR and Calorie Calculator

Enter your age, sex, height, weight and activity level to estimate your basal metabolic rate — the calories your body uses at rest — and the daily calories that would keep your weight steady. It uses the Mifflin-St Jeor equation, the estimate most dietitians use. A 35-year-old woman, 168 cm and 68 kg, has a BMR of about 1,394 kcal.

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Updated

Please note

These are estimates for general information, not medical or nutritional advice. If you are pregnant, have a health condition, take medication that affects weight, or are planning a significant diet change, speak to a doctor or registered dietitian.

How to use the BMR and Calorie Calculator

  1. 1Choose metric or imperial units and enter your age, height and weight.
  2. 2Choose the sex the equation should use.
  3. 3Pick the activity level closest to a typical week.
  4. 4Read your BMR and the maintenance calories, and compare activity levels in the table.

How it works

BMR is estimated with the Mifflin-St Jeor equation, published in the American Journal of Clinical Nutrition in 1990: 10 × weight in kg + 6.25 × height in cm − 5 × age in years, then + 5 for men or − 161 for women.

Maintenance calories, often called total daily energy expenditure (TDEE), multiply BMR by an activity factor from 1.2 for sedentary to 1.9 for very physical work and training. These factors are the standard ones used alongside the equation, but they are broad bands: choose the one that matches an ordinary week, not your most active one.

Both figures are population averages. Body composition, genetics, health conditions and medication can move an individual's real needs well above or below the estimate. Weight trends over a few weeks are a better guide than any formula.

The equation was developed for adults, so ages under 15 are not calculated. Everything is calculated in your browser.

The formula

BMR = 10 × weight + 6.25 × height − 5 × age + s maintenance = BMR × activity factor
weight
kilograms; height — centimetres; age — years
s
+5 for men, −161 for women
activity factor
1.2, 1.375, 1.55, 1.725 or 1.9

Worked example

A 35-year-old woman, 168 cm, 68 kg, lightly active

  1. BMR = 10 × 68 + 6.25 × 168 − 5 × 35 − 161
  2. = 680 + 1,050 − 175 − 161 = 1,394 kcal
  3. Maintenance = 1,394 × 1.375 ≈ 1,917 kcal

Result: About 1,394 kcal at rest and about 1,917 kcal a day to maintain weight.

Tips and common mistakes

  • Pick the activity level for a normal week, not your best one; overestimating activity is the most common mistake.
  • Re-calculate after a significant change in weight, since BMR falls as weight falls.
  • Use the estimate as a starting point and adjust based on how your weight changes over several weeks.
  • Weigh yourself at the same time of day when tracking trends.

Frequently asked questions

What is the difference between BMR and TDEE?
BMR is the energy your body uses at complete rest just to keep running. TDEE, or maintenance calories, adds everything you do in a day, from walking to exercise.
Is Mifflin-St Jeor accurate?
It is the most widely recommended equation for adults, but it is an estimate. Individual results commonly differ from it, which is why progress over a few weeks is the real test.
How many calories should I eat to lose weight?
That depends on your health and goals; a doctor or registered dietitian can advise. Eating below your maintenance estimate leads to weight loss over time, but very low intakes are not safe without supervision.
Why does the equation ask for sex?
On average, men and women of the same height and weight have different body composition, so the equation uses a different constant. Choose the one that best fits your body, or ask a clinician if neither does.
Does it work for athletes?
Very muscular people often burn more than the equation predicts, because it does not know body composition. Treat the result as a lower estimate.
Is my information saved?
No. Everything is calculated in your browser and nothing is stored or sent.
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