How we calculate your calories
First we estimate your basal metabolic rate (BMR), the energy you burn at rest, using the Mifflin-St Jeor equation. The Academy of Nutrition and Dietetics recommends it as the most accurate for healthy adults.
Then we multiply your BMR by an activity factor to get your total daily energy expenditure (TDEE): your maintenance calories.
| Activity level | Factor |
|---|---|
| Sedentary (little or no exercise) | 1.2 |
| Light (1–3 days a week) | 1.375 |
| Moderate (3–5 days a week) | 1.55 |
| Very active (6–7 days a week) | 1.725 |
| Extra active (physical job or twice a day) | 1.9 |
How many calories to eat to lose weight
A pound of body fat holds roughly 3,500 calories. A 500-calorie daily deficit leads to about 1 lb (0.45 kg) of weight loss per week, a sustainable pace for most people. Bigger deficits work faster but increase hunger and the risk of losing muscle.
And to build muscle
To gain muscle while keeping fat gain low, a small surplus of 250–500 calories a day is enough, combined with strength training and enough protein. Split those calories with our macro calculator.
Why the result is an estimate
Formulas predict the average well, but any one person can be 10% above or below. Treat the result as a starting point: track your weight for 2–3 weeks and adjust by 100–200 calories based on the trend.
Frequently asked questions
What is TDEE?
Total daily energy expenditure: the calories you burn in a day from your basal metabolism, digestion, daily movement and exercise. Eat that amount and your weight stays stable.
Which calorie formula is the most accurate?
For adults whose body-fat percentage is unknown, Mifflin-St Jeor performs best in comparison studies. If you know your body fat, Katch-McArdle can be slightly more precise.
Should I eat back the calories I burn exercising?
No. The activity factor already includes your usual exercise. Adding your fitness tracker's calories on top would count them twice.
Is eating under 1,200 calories dangerous?
For most adults, staying below 1,200 calories (women) or 1,500 (men) for long periods makes it hard to get enough vitamins, minerals and protein. Only do it under medical supervision.
Results are estimates for general information only and are not a substitute for advice from a doctor, registered dietitian or qualified coach.