Calorie calculator: how many do I need a day?
Estimate how many calories your body uses in a day from your age, sex, weight, height and activity level. We use the Mifflin-St Jeor equation, the one most dietitians use, and FAO/WHO activity levels.
The formula
First, resting energy expenditure is estimated with the Mifflin-St Jeor equation (1990):
- Women: 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) − 161
- Men: 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) + 5
Then it is multiplied by the physical activity level. FAO, WHO and UNU (2004) classify a sedentary lifestyle at 1.40–1.69, a moderately active one at 1.70–1.99 and a vigorous one at 2.00–2.40. The calculator uses these values:
| Level | What it looks like | Factor |
|---|---|---|
| Very inactive | sitting most of the day, no exercise | × 1.4 |
| Sedentary | desk job, some walking | × 1.55 |
| Moderately active | exercise 3–5 days or a job on your feet | × 1.85 |
| Very active | hard training or heavy physical work | × 2.2 |
Examples: how many calories a person needs
| Person | At rest | Very inactive | Sedentary | Moderately active | Very active |
|---|---|---|---|---|---|
| Woman, 30 years, 55 kg, 160 cm | 1,239 | 1,735 | 1,920 | 2,292 | 2,726 |
| Woman, 30 years, 65 kg, 160 cm | 1,339 | 1,875 | 2,075 | 2,477 | 2,946 |
| Woman, 30 years, 80 kg, 165 cm | 1,520 | 2,128 | 2,356 | 2,812 | 3,345 |
| Woman, 50 years, 70 kg, 160 cm | 1,289 | 1,805 | 1,998 | 2,385 | 2,836 |
| Man, 30 years, 70 kg, 175 cm | 1,649 | 2,308 | 2,556 | 3,050 | 3,627 |
| Man, 30 years, 85 kg, 175 cm | 1,799 | 2,518 | 2,788 | 3,328 | 3,957 |
| Man, 30 years, 100 kg, 180 cm | 1,980 | 2,772 | 3,069 | 3,663 | 4,356 |
| Man, 50 years, 85 kg, 175 cm | 1,699 | 2,378 | 2,633 | 3,143 | 3,737 |
For comparison: food labels use 2,000 calories as a general reference. A taco has 212 calories and a slice of pizza, 270. Calories for every food are in the calorie table.
Frequently asked questions
How many calories do I need a day?
It depends on your age, sex, size and activity. For example, a sedentary 30-year-old woman who weighs 65 kg (143 lb) and is 160 cm (5'3") tall uses about -395 calories a day; a sedentary 30-year-old man of 85 kg (187 lb) and 175 cm (5'9"), about -60.
What is basal metabolic rate?
It is what the body uses at rest to breathe, keep its temperature and run its organs. It is usually the largest part of daily energy use; movement adds the rest.
How accurate is the calculator?
It is an estimate for the general population. The Mifflin-St Jeor equation is close for most healthy adults, but it can be off for very muscular people, people with obesity, older adults, pregnant people or those with a medical condition.
Why do labels say 2,000 calories?
It is a round reference value for comparing foods on the label, not a personal recommendation. Both the US FDA and Mexico's NOM-051 use it.
This is a general estimate, not personal advice. To lose or gain weight, during pregnancy or with a medical condition, talk to a health professional.
Sources
Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990;51(2):241-247.
FAO/WHO/UNU. Human energy requirements: report of a Joint FAO/WHO/UNU Expert Consultation. Rome, 2004.