Calorie Calculator

How to estimate your daily calories

Choose metric or imperial units, and your sex.
Enter your age, weight and height.
Pick the activity level that best describes a typical week.
Read your maintenance calories, your resting needs, and gentle targets to lose or gain weight.

The formula

Resting needs (basal metabolic rate, BMR) use the Mifflin-St Jeor equations from 1990:

Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5
Women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161

Daily needs, often called TDEE (total daily energy expenditure), are BMR multiplied by a physical activity level. The equations were fitted to 498 healthy adults aged 19 to 78, so results for people outside that range, or with very high muscle mass, are less certain.

Activity levels

The multipliers are the FAO/WHO/UNU examples for three lifestyles:

Lifestyle	Multiplier	Range	Typical day
Sedentary or lightly active	1.53	1.40–1.69	Desk job, little walking or exercise
Active or moderately active	1.76	1.70–1.99	On your feet at work, or about an hour of exercise most days
Vigorously active	2.25	2.00–2.40	Heavy manual work or several hours of sport a day

Worked example

A 30-year-old man, 80 kg and 180 cm, with a desk job:

BMR = 10 × 80 + 6.25 × 180 − 5 × 30 + 5 = 800 + 1,125 − 150 + 5 = 1,780 kcal.
Maintenance = 1,780 × 1.53 ≈ 2,723 kcal a day.
Gentle weight loss: 2,723 − 500 ≈ 2,223 kcal a day.
Gentle weight gain: 3,023 to 3,223 kcal a day.

Losing or gaining weight

The loss target is 500 kcal a day below maintenance, the gentle end of the NHLBI's advice to cut 500 to 1,000 kcal a day for a loss of about 1 to 2 pounds (0.5 to 1 kg) a week. The NHS also suggests aiming for 0.5 to 1 kg a week. The gain range adds 300 to 500 kcal a day, as the NHS suggests for gaining weight gradually. Weight is part of the formula, so your needs change as your weight does: recalculate every few kilos.

Not medical advice

These are estimates from averages, not a diet plan. If you're pregnant or breastfeeding, have diabetes, kidney disease or an eating disorder, or want to lose a lot of weight, talk to a doctor or registered dietitian before changing what you eat.

Sources

Each link was last checked on 7 October 2026.

A new predictive equation for resting energy expenditure in healthy individuals (Mifflin, St Jeor et al.), The American Journal of Clinical Nutrition (1990): the Mifflin-St Jeor equations, derived from 498 healthy adults aged 19 to 78.
Human energy requirements, chapter 5: Energy requirements of adults, FAO, WHO and UNU (2004): physical activity levels (PAL) of 1.53, 1.76 and 2.25 for sedentary, active and vigorous lifestyles.
The Practical Guide: Identification, Evaluation, and Treatment of Overweight and Obesity in Adults, US National Heart, Lung, and Blood Institute (2000): cutting 500 to 1,000 kcal a day for a loss of 1 to 2 pounds a week.
Overweight and obesity in adults, NHS (2026): losing weight steadily, 0.5 to 1 kg a week.
Healthy ways to gain weight, NHS (2023): adding around 300 to 500 kcal a day to gain weight gradually.

Common uses

Planning a gentle weight loss. See roughly how many calories a day keep your weight steady, and a target about 500 kcal lower to lose weight gradually.
Gaining weight after illness. Find a daily target 300 to 500 kcal above maintenance, the gradual increase the NHS suggests for gaining weight.
Reading food labels. Compare the calories on packaged food with your own daily estimate rather than the generic 2,000 kcal on the label.

Questions

How many calories do I need a day?

It depends on your size, age, sex and how active you are. The NHS uses about 2,000 kcal for an average woman and 2,500 kcal for an average man as a guide; this calculator estimates your own figure by working out your resting needs and multiplying them by your activity level.

What is BMR?

Basal metabolic rate: the energy your body uses at rest to breathe, circulate blood and keep warm. It's usually the largest part of the calories you burn each day. The calculator estimates it with the Mifflin-St Jeor equation: 10 × weight (kg) + 6.25 × height (cm) − 5 × age, then + 5 for men or − 161 for women.

Why Mifflin-St Jeor rather than Harris-Benedict?

Mifflin-St Jeor was fitted in 1990 to measured resting energy in 498 healthy adults of normal weight and with obesity. In that study the older Harris-Benedict equations, from 1919, overestimated measured resting energy by about 5%.

How many calories should I cut to lose weight?

US guidance from the NHLBI is to eat 500 to 1,000 kcal a day less than you burn, for a loss of about 0.5 to 1 kg (1 to 2 lb) a week, which matches the NHS's advice to lose weight steadily. The calculator shows the gentler 500 kcal step. Weight loss usually slows over time, so treat it as a starting point.

How are activity levels chosen?

They come from the FAO, WHO and UNU report on human energy requirements, which describes three lifestyles by their physical activity level: about 1.53 times resting needs for sedentary or light activity, 1.76 for active, and 2.25 for vigorous.