How to use this tool
- Choose units and enter your sex, age, height and weight.
- Pick the activity level that matches a normal week.
- Read your maintenance calories and the targets for losing or gaining weight.
The Mifflin-St Jeor equation
Published in 1990, this equation is the one most dietitians use to estimate resting energy needs, and studies have found it more accurate than the older Harris-Benedict formula for most adults.
Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5
Women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161
BMR is what your body burns at complete rest. Multiplying it by an activity factor gives total daily energy expenditure (TDEE), the calories needed to keep your weight steady.
Losing weight safely
A deficit of about 500 kcal a day typically leads to roughly 0.5 kg (1 lb) of weight loss a week at first, though the rate slows over time as the body adapts. The NIH Body Weight Planner models this slowing more precisely. Very low calorie diets should only be followed with medical supervision.
Why the number is an estimate
Two people with the same age, height and weight can burn quite different amounts, depending on muscle mass, genetics and daily movement. Use the figure as a starting point, track your weight for two to three weeks and adjust.
Frequently asked questions
How many calories should I eat to lose weight?
Roughly 500 kcal below your maintenance figure, which often leads to about 0.5 kg (1 lb) loss per week at first.
What is the difference between BMR and TDEE?
BMR is energy used at rest. TDEE adds the energy used for daily activity and exercise.
Which formula is most accurate?
The Mifflin-St Jeor equation is the most widely recommended for healthy adults.
Is 1,200 calories a day safe?
It is often given as a lower limit for women. Going lower should be done only with medical supervision.
Sources and references
- Mifflin MD et al. A new predictive equation for resting energy expenditure. Am J Clin Nutr 1990;51:241–7
- NHS: Understanding calories
- NIH Body Weight Planner