Calorie Calculator
The figures on food packaging are population averages, not personal targets. This calculator works out what your own body needs from your measurements and how active you actually are.
Formula
BMR (men) = 10w + 6.25h − 5a + 5 · BMR (women) = 10w + 6.25h − 5a − 161
- w = weight in kg, h = height in cm, a = age in years
- Mifflin-St Jeor, the equation most used clinically
Man, 80 kg, 180 cm, 30: 800 + 1,125 − 150 + 5 = 1,780 kcal at rest
How Your Requirement Is Calculated
Two steps. First your Basal Metabolic Rate, using the Mifflin-St Jeor equation:
- Men: (10 × kg) + (6.25 × cm) − (5 × age) + 5
- Women: (10 × kg) + (6.25 × cm) − (5 × age) − 161
Then multiply by an activity factor from 1.2 (sedentary) to 1.9 (intense daily training) to get maintenance calories.
Setting a Target
A deficit of about 500 calories a day corresponds to roughly 0.45 kg (1 lb) of loss per week; a surplus of 500 does the reverse. Larger deficits cost muscle alongside fat and are far harder to sustain.
Recalculate every 4–5 kg: a lighter body burns less, so the deficit that worked at the start slowly becomes maintenance.
Where Estimates Go Wrong
The activity multiplier moves the answer far more than your measurements do — the difference between "lightly active" and "extra active" can be 900 calories a day. Most people overestimate. Pick the level you think applies, then drop down one and see whether your weight holds steady.
Quick Reference
| Profile | BMR | Sedentary | Moderately active |
|---|---|---|---|
| Man, 80 kg, 180 cm, 30 | 1,780 | 2,136 | 2,759 |
| Man, 70 kg, 175 cm, 40 | 1,599 | 1,918 | 2,478 |
| Woman, 65 kg, 165 cm, 30 | 1,370 | 1,644 | 2,124 |
| Woman, 60 kg, 160 cm, 40 | 1,239 | 1,487 | 1,920 |
Frequently Asked Questions
- How many calories should I eat to lose weight?
- Around 500 below your maintenance level for roughly a pound a week. Intakes below about 1,500 for men or 1,200 for women should only be undertaken with medical supervision.
- Is 2,000 calories a day right for me?
- Only by coincidence. It is a labelling reference figure. A tall, active 25-year-old and a shorter, sedentary 60-year-old need very different amounts.
- Why has my weight stopped falling?
- Usually water weight masking fat loss, a maintenance level that has fallen with your weight, or portion estimates creeping up. Judge progress on a weekly average.
- How accurate is this?
- Individual metabolic rates vary by roughly 10 per cent either side of the prediction. Treat the number as a starting point to calibrate against a few weeks of real results.