Calorie Calculator
Estimate the daily calories you need to lose, maintain or gain weight.
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How to use this calculator
Choose your sex (the formula uses it), your units and your activity level, then enter your age, weight and height. You get your resting calories (BMR), your daily maintenance calories, and targets for gentle weight loss or gain.
How it's calculated
Mifflin–St Jeor: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5 for men or − 161 for women. Daily calories = BMR × activity factor (1.2 to 1.9). About 7,700 calories equals 1 kg of body weight. Targets never go below 1,200 (women) or 1,500 (men) calories.
Worked example
A 30-year-old woman, 65 kg, 165 cm, lightly active: BMR = 650 + 1031 − 150 − 161 ≈ 1,370 calories. Maintenance = 1,370 × 1.375 ≈ 1,890 calories a day.
Frequently asked questions
How accurate is this?
It is an estimate for healthy adults. Real needs vary with muscle, genetics and health, so use it as a starting point and adjust to your results.
Is it safe to eat much fewer calories?
Very low calorie diets can be harmful. For weight loss plans, pregnancy, medical conditions or under 18, please talk to a doctor or dietitian.
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Last updated October 2026. Results are for learning and guidance; always check important work. Calculations run in your browser and are not stored.