Your TDEE (total daily energy expenditure) is the number of calories you burn in a day, including exercise. To estimate it, work out your basal metabolic rate (BMR) with the Mifflin-St Jeor equation, then multiply by an activity factor between 1.2 and 1.9. Eating around your TDEE keeps your weight steady; eating less or more moves it down or up.
What BMR and TDEE mean
BMR is the energy your body uses at rest to breathe, circulate blood and keep warm. TDEE adds everything else: walking, work, exercise and digesting food. Most people’s TDEE is well above their BMR, which is why you cannot judge your needs from BMR alone.
The Mifflin-St Jeor equation
The calculator uses this widely used equation for adults:
- Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5
- Women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161
Then TDEE = BMR × activity multiplier.
| Activity level | Multiplier |
|---|---|
| Little or no exercise | 1.2 |
| Light exercise, 1 to 3 days a week | 1.375 |
| Moderate exercise, 3 to 5 days a week | 1.55 |
| Hard exercise, 6 to 7 days a week | 1.725 |
| Very hard exercise or a physical job | 1.9 |
Worked example
Take a 35-year-old woman, 165 cm and 65 kg, who exercises lightly one to three days a week.
- BMR: 10 × 65 + 6.25 × 165 − 5 × 35 − 161 = 1,345 kcal
- TDEE: 1,345 × 1.375 = about 1,850 kcal a day
From that maintenance figure, the Calorie and TDEE tool suggests roughly 1,575 kcal to lose 0.25 kg a week or 1,300 kcal to lose 0.5 kg a week. It does not show targets below 1,200 kcal.
Turning TDEE into a goal
A moderate deficit is generally easier to stick to than a steep one. To lose weight, eat below your TDEE; to gain, eat above it. The weekly figures above are estimates, since the equation predicts averages and individuals differ.
Treat the result as a starting point. Track your weight and energy over two to four weeks, then adjust by 100 to 200 kcal if progress is not what you expected. Your weight is also only one measure, so it can help to look at BMI explained: what it tells you and what it doesn't and Body fat percentage: how it's measured and what's typical alongside it.
Where the calories come from
Calories come from protein (4 kcal per gram), carbohydrate (4 kcal per gram), fat (9 kcal per gram) and alcohol (7 kcal per gram). Once you have a daily target, you can split it into those nutrients. Macros for beginners: protein, carbs and fat explains how, and the Calories and macros tool converts a calorie target into grams.
Why your real needs may differ
- Muscle burns more than fat at rest, so two people of equal weight can differ.
- Activity level is the biggest guess. Many people overestimate it, so pick the lower level if unsure.
- Age, sleep, stress and some medical conditions or medicines affect energy needs.
- The equation is for adults and does not apply to pregnancy, breastfeeding or children.
Note: This is general information, not medical advice. Speak to a GP or dietitian before cutting calories sharply, or if you have a health condition or a history of disordered eating.
Common questions about eating at a deficit or surplus
Smaller changes tend to be easier to keep up. Cutting 250 to 500 kcal below TDEE is the kind of gap the calculator shows, and it usually feels more manageable than a crash diet. Do not eat below the amounts your GP or dietitian recommends, and avoid very low targets without supervision.
For gaining weight, a modest surplus plus regular strength training gives your body a reason to build muscle rather than only add fat. Either way, re-run the calculation when your weight changes by a few kilograms, because your maintenance figure moves with your body size.
Try the calculator
Use Calorie and TDEE to estimate your BMR and daily calories for losing, keeping or gaining weight, then Calories and macros to turn a target into grams of protein, carbohydrate and fat. Both give estimates.
Open the free Calorie and TDEE
Frequently asked questions
How many calories should I eat a day?
It depends on your age, sex, size and activity. The equation above gives an estimate of what keeps your weight steady.
Is BMR the same as TDEE?
No. BMR is your resting energy use. TDEE is BMR plus activity, so it is always higher.
Which activity level should I choose?
Choose honestly based on your typical week, including your job. If you are between two levels, pick the lower one and adjust after tracking.
How accurate is the Mifflin-St Jeor equation?
It is a good estimate for many adults, but it is still an average. Use it as a starting point and adjust to your real results.