Calorie Calculator
Find how many calories you need a day to keep, lose or gain weight, from your age, size and activity.
About the Calorie Calculator
Daily calorie needs start with your basal metabolic rate (Mifflin-St Jeor equation) multiplied by an activity factor. That gives the calories to stay the same weight.
A deficit of about 7,700 kcal is often used per kilogram of fat (3,500 kcal per pound), so 500 kcal a day less loses about 0.5 kg (1 lb) a week at first. Weight loss slows over time as your body adapts, so treat the timeline as a starting estimate.
The formula
Calories = BMR × activity factor ± goal adjustment
- BMR (Mifflin-St Jeor)
- 10W + 6.25H − 5A + 5 (men) or − 161 (women)
- 1 kg of fat
- ≈ 7,700 kcal
Worked example
Example: To maintain your weight = 2,989 kcal/day
- Inputs: Units: lb / ft; Sex: Male; Age: 39 years; Height: 6 ft; and: 10 in; Weight: 180 lb; Activity level: Moderate (exercise 3–5 days/week).
- Formula: Calories = BMR × activity factor ± goal adjustment
- Result: To maintain your weight = 2,989 kcal/day
- Resting (BMR): 1,928 kcal
- In kilojoules: 12,505 kJ
Things to keep in mind
- This is an estimate for general information, not medical advice. Talk to a doctor or other qualified professional about your health.
- Most adults shouldn't go below about 1,200 kcal (women) or 1,500 kcal (men) a day without medical supervision.
Questions people ask
Why is my weight loss slower than predicted?
Your metabolism and activity fall a little as you lose weight. Re-run the calculator every few kilograms.
Are all calories equal?
For weight change, roughly; for health and fullness, protein, fibre and whole foods help a lot.