How many calories do you need?
Work out your TDEE, the calories your body uses in a day, and your BMR, the calories it uses at rest. It uses the method the UK's Scientific Advisory Committee on Nutrition uses.
For adults aged 18 and over. Please don't use it if you're pregnant or breastfeeding, or have or think you may have an eating disorder.
Nothing is saved or sent. This stays on your device.
- At rest (your BMR)
- 1,500 kcal
- Activity level used
- Average, 1.63
The NHS advises eating and drinking fewer calories than your body uses, and aiming to lose 0.5 to 1kg (1 to 2lbs) a week. NICE sets no one figure for everyone; many of the studies it reviewed used 500 to 800 kcal a day less.
For you, 500 kcal a day less than your estimate would be about 1,940 kcal a day.
Want to check your weight for your height first? Check your BMI.
What is TDEE?
TDEE (total daily energy expenditure) is the calories your body uses in a day: the energy it uses at rest, plus what you use moving about and being active. Eat and drink about that many calories and your weight tends to stay the same; eat fewer and you tend to lose weight.
Your BMR (basal metabolic rate) is the part your body uses at rest, to breathe, keep warm and keep your organs working. For most adults it is the biggest part of the day's total.
How this calculator works
Your BMR comes from the Henry equations, from your weight, height, age and sex. Your TDEE is your BMR multiplied by an activity level: 1.49 for less active, 1.63 for average and 1.78 for more active. Both are what the UK's Scientific Advisory Committee on Nutrition uses to set the country's energy reference values.
If you're not sure which activity level fits, choose average. The result is rounded to the nearest 10 calories.
How accurate is it?
It is an estimate. In the committee's comparison against measured data, the Henry equations put about 7 in 10 people within 10% of their measured resting energy, and an activity level is a broad band.
Use the result as a starting point. If your weight changes when you expected it to stay steady, your own number is a little higher or lower than the estimate.
How many calories does the NHS say you need?
As a guide, the NHS says an average man needs about 2,500 kcal a day and an average woman about 2,000 kcal a day. Your own figure depends on your age, weight, height and how active you are.
For how many adults in the UK are overweight, by area, see our UK obesity statistics.
Common questions
TDEE stands for total daily energy expenditure: the calories your body uses in a day. It is the energy you use at rest (your BMR) plus what you use moving about and being active. If you eat and drink about this many calories, your weight tends to stay the same.
BMR stands for basal metabolic rate: the calories your body uses at rest, to breathe, keep warm and keep your organs working. For most adults it is the biggest part of the calories they use in a day.
Fewer than your body uses. The NHS advises eating and drinking fewer calories than your body uses and aiming to lose 0.5 to 1kg (1 to 2lbs) a week. NICE does not set one figure for everyone; many of the studies it reviewed used 500 to 800 kcal a day less than people used. The NHS describes a very low calorie diet as under 800 or 1,200 calories a day and says it is not suitable or safe for everyone, so speak to your GP before cutting that far.
As a guide, the NHS says an average man needs about 2,500 kcal a day and an average woman about 2,000 kcal a day. Your own figure depends on your age, weight, height and how active you are, which is what this calculator estimates.
It is an estimate. The equations used here put about 7 in 10 people within 10% of their measured resting energy, and the activity level is a broad band. Treat the result as a starting point: if your weight changes when you expected it to stay steady, your own number is higher or lower than the estimate.
The Henry equations, from weight, height, age and sex, which the UK's Scientific Advisory Committee on Nutrition uses, multiplied by the Committee's activity levels for adults: 1.49 for less active, 1.63 for average and 1.78 for more active.
No. Your energy needs change during pregnancy and breastfeeding, and this calculator does not allow for them. Ask your midwife, health visitor or GP.
No. Nothing is saved or sent. The sums run on your device and the numbers stay there.
Sources
- Scientific Advisory Committee on Nutrition, Dietary Reference Values for Energy (2011): table 18 (the Henry equations), summary S43 (activity levels) and table 20 (accuracy).
- Henry CJ. Basal metabolic rate studies in humans: measurement and development of new equations. Public Health Nutrition 2005;8(7A):1133-52.
- NHS, Understanding calories.
- NHS, Obesity: treatment.
- NICE guideline NG246, Overweight and obesity management (2025), recommendation 1.16.3 and its rationale.
Read 25 October 2026.
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