Calorie (TDEE) calculator
This calculator works out an estimated daily calorie requirement, or TDEE, from height, weight, age, sex and activity level, using the Mifflin-St Jeor equation to calculate basal metabolic rate. It also shows a calorie range for losing or gaining weight. Figures are general estimates, not dietary advice, and a GP or dietitian can advise on personal changes.
How is TDEE calculated?
The calculator first works out Basal Metabolic Rate using the Mifflin-St Jeor equation.
For men, BMR is ten times weight in kilograms, plus 6.25 times height in centimetres, minus five times age, plus five.
For women, the equation ends by subtracting 161 instead of adding five.
| Activity level | Factor |
|---|---|
| Sedentary (little or no exercise) | x1.2 |
| Lightly active (1 to 3 days a week) | x1.375 |
| Moderately active (3 to 5 days a week) | x1.55 |
| Very active (6 to 7 days a week) | x1.725 |
| Extra active (hard training or physical job) | x1.9 |
Multiplying BMR by the activity factor for a typical week gives Total Daily Energy Expenditure, the maintenance calorie figure.
Cutting about 500 kcal a day from maintenance, or adding 500 kcal, gives an estimated range for gradual weight loss or gain.
What would this look like for an example person?
Take a 35-year-old man who is 178 cm tall and weighs 82 kg and trains most days.
His BMR from the Mifflin-St Jeor equation comes to about 1,763 kcal.
Multiplying that by the moderately active factor of 1.55 gives a maintenance figure of about 2,733 kcal.
Subtracting 500 kcal gives an estimated 2,233 kcal for gradual weight loss, and adding 500 kcal gives about 3,233 kcal for gradual gain.
These are estimates, and a GP or dietitian should be consulted before making significant dietary changes.
Common questions
How many calories do I need a day?
It depends on your size, age, sex and how active you are. As a rough NHS guide, an average woman needs about 2,000 kcal a day and an average man about 2,500 kcal to maintain weight. This tool tailors that to your own figures using the Mifflin-St Jeor equation.
What is TDEE?
Total Daily Energy Expenditure is the calories you burn in a day, at rest and through activity. It is your Basal Metabolic Rate multiplied by an activity factor, from 1.2 for a sedentary day up to 1.9 for very hard training or a physical job.
How big a calorie deficit should I aim for?
A deficit of about 500 kcal a day tends to produce roughly half a kilogram of weight loss a week, which the NHS considers a safe and sustainable pace. A gentler 250 kcal cut is easier to sustain. Very large deficits are hard to maintain and can be counterproductive.
Is the calorie figure exact?
No. Mifflin-St Jeor is a well-regarded estimate, but everyone burns energy slightly differently, so treat the number as a starting point. Track your weight over two or three weeks and adjust the intake up or down if the trend is not what you want.
Should I eat back exercise calories?
The activity factor already includes your typical exercise, so you should not add extra calories on top for the same workouts. Only adjust if your activity genuinely changes, for example a new training block or a much more active job.
How is TDEE calculated?
TDEE is calculated in two steps. First, the Mifflin-St Jeor equation works out Basal Metabolic Rate from height, weight, age and sex. Second, that figure is multiplied by an activity factor, ranging from 1.2 for a sedentary day to 1.9 for very hard training or a physical job, to give an estimated daily calorie requirement.
What would this look like for an example person?
For a 35-year-old man who is 178 cm tall and weighs 82 kg, the Mifflin-St Jeor equation gives a BMR of about 1,763 kcal. Multiplying by the moderately active factor of 1.55 gives an estimated maintenance figure of about 2,733 kcal a day. A 500 kcal cut points to roughly 2,233 kcal for gradual weight loss, and a 500 kcal increase to about 3,233 kcal for gradual gain.
Sources & Rate Verification
Rates verified against official statutory guidance on 6 September 2026.