Calorie Calculator

Calories a day for your goal: 1,850 kcal
To keep your weight steady: 1,850 kcal
Used at complete rest (BMR): 1,345 kcal
Goal in kilojoules: 7,739 kJ
Safe minimum: Your goal is above the usual safe minimum

What it does

Estimate how many calories you burn in a day, and how many to eat to keep your weight steady, lose weight or gain it gradually. It uses your age, sex, height, weight and how active you are, with the Mifflin-St Jeor equation that dietitians commonly use.

How to use it

Sex: The equation differs slightly by sex, because of typical differences in body make-up.
Age: Your age in years. The equation is for adults; children and teenagers need different guidance.
Height: Your height without shoes.
Weight: Your current weight.
Activity level: Light means exercise 1 to 3 days a week, moderate 3 to 5, very active hard exercise 6 or 7 days, and extra active a physical job plus training. Most people overestimate: a desk job with a few walks a week is 'little or no exercise'.
Goal: 0.25 kg is about ½ lb, 0.5 kg about 1 lb and 0.75 kg about 1½ lb. Slow and steady is easier to keep up: the NHS suggests losing no more than 0.5 to 1 kg (1 to 2 lb) a week.

Common uses

Setting a sensible daily calorie target.
Checking whether a diet plan's numbers are realistic.
Checking whether your weight is in the healthy range. Try the BMI Calculator
Counting the alcohol units (and calories) in drinks. Try the Alcohol Units Calculator (UK)

The formula

BMR (women) = 10 × weight + 6.25 × height − 5 × age − 161BMR (men) = 10 × weight + 6.25 × height − 5 × age + 5Calories to stay the same = BMR × activity levelGoal = that ± 1,100 kcal a day for each kg a week

Where:

BMR: basal metabolic rate: the energy your body uses at complete rest
weight, height: in kg and cm
Activity level: from 1.2 (little exercise) to 1.9 (extra active)
7,700 kcal: roughly the energy in 1 kg of body fat

An estimate for adults: real needs vary from person to person by around 10%. Not for use in pregnancy. Speak to a GP or dietitian for advice tailored to you.

Worked example

For a man aged 30 years, 180 cm tall and weighing 80 kg:

BMR: 10 × 80 + 6.25 × 180 − 5 × 30 + 5 = 1,780 kcal
With moderate activity: 1,780 kcal × 1.55 = 2,759 kcal to stay the same
To lose about 0.5 kg a week: 2,759 kcal − 550 = 2,209 kcal

Questions people ask

How many calories should I eat a day?

The NHS guide is about 2,000 kcal a day for women and 2,500 for men to stay the same weight, but it depends on your size, age and activity, which is what this calculator allows for.

How accurate is it?

The Mifflin-St Jeor equation is one of the most reliable for adults, but it's still an estimate. Track your weight for a few weeks and adjust by 100 to 200 kcal if it isn't changing as expected.

Why won't it go below 1,200 or 1,500 calories?

Eating less than about 1,200 kcal a day for women or 1,500 for men makes it hard to get enough nutrients, so it isn't advised without medical supervision. If your goal would go lower, it shows the minimum instead.

Last checked 26 October 2026