Calorie (TDEE) calculator
See how many calories you need in a day to maintain, lose or gain weight, based on your own height, weight, age, sex and activity level.
How it works
The tool starts with your Basal Metabolic Rate, the energy your body uses at complete rest, using the Mifflin-St Jeor equation. For men that is ten times weight in kilograms, plus 6.25 times height in centimetres, minus five times age, plus five. For women the final term is minus 161 instead. It then multiplies that BMR by an activity factor, from 1.2 for a mostly sedentary day up to 1.9 for hard daily training, to give your Total Daily Energy Expenditure. That TDEE is the calories needed to hold your weight steady.
For weight change the tool adjusts that maintenance figure. Cutting about 500 kcal a day usually loses around half a kilogram a week, the pace the NHS treats as safe and sustainable, while adding 500 kcal supports gradual gain. These are averages, so the honest test is the scales over two to three weeks: if the trend is flat when you want loss, trim a little more, and the other way round.
Worked example
Take a 35-year-old man, 178 cm and 82 kg, who trains three to five days a week. His BMR works out at about 1,763 kcal. Multiplied by the moderate activity factor of 1.55, that is roughly 2,733 kcal to maintain. To lose weight at a steady pace he would aim for about 2,233 kcal a day, and to gain he would eat nearer 3,233 kcal. A gentler cut of 2,483 kcal is often easier to keep up over months.
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.