TDEE is your basal metabolic rate multiplied by an activity factor. The Mifflin-St Jeor equation gives BMR as 10 × weight (kg) + 6.25 × height (cm) − 5 × age, plus 5 for men or minus 161 for women. A sedentary 30-year-old man of 80 kg and 180 cm has a BMR of 1,780 and a TDEE of about 2,136 kcal.
Total Daily Energy Expenditure is the number of calories your body gets through in a day. It is the figure every diet plan is implicitly built around: eat roughly that much and your weight holds steady, eat consistently below it and you lose, above it and you gain. This calculator estimates it from the Mifflin-St Jeor equation. It answers a different question from the BMI calculator: BMI says whether your weight is in a healthy band for your height, TDEE says how much energy that body uses to stay where it is.
TDEE Calculator
Checked against: Male, 30, 80 kg, 180 cm, sedentary: BMR 1,780 kcal, TDEE 2,136 kcal Last reviewed:
- BMR (at rest)
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- To lose weight
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- To maintain
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- To gain weight
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Sources and method
- Mifflin MD, St Jeor ST, et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990
- Basal metabolic rate - Wikipedia
A screening estimate for general information, not a diagnosis or medical advice. Talk to a doctor or registered dietitian before acting on it.
How the estimate is built
The calculation happens in two steps.
Step one: basal metabolic rate
BMR is what your body burns simply existing — running your heart, brain, liver and kidneys and holding your temperature steady. It is the largest single component of daily expenditure, typically 60% to 70% of the total.
Men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5
Women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161
Step two: the activity multiplier
BMR is then multiplied by a factor reflecting how much you move:
| Activity level | Multiplier | Description | Man, 80 kg / 180 cm | Woman, 65 kg / 165 cm |
|---|---|---|---|---|
| Sedentary | ×1.2 | Desk job, little or no deliberate exercise | 2,136 kcal | 1,644 kcal |
| Light | ×1.375 | Light exercise one to three days a week | 2,448 kcal | 1,884 kcal |
| Moderate | ×1.55 | Moderate exercise three to five days a week | 2,759 kcal | 2,124 kcal |
| Active | ×1.725 | Hard exercise six or seven days a week | 3,071 kcal | 2,364 kcal |
| Very active | ×1.9 | Physical job, or training twice a day | 3,382 kcal | 2,603 kcal |
A worked example
A 30-year-old man, 80 kg and 180 cm tall:
- (10 × 80) = 800
- (6.25 × 180) = 1,125
- (5 × 30) = 150
- BMR = 800 + 1,125 − 150 + 5 = 1,780 calories
Applying the multipliers gives a TDEE of 2,136 if sedentary, 2,448 on light activity, 2,759 on moderate, 3,071 if active, and 3,382 at the top level. The gap between the bottom and top of that range is over 1,200 calories a day, which is why choosing the activity level honestly matters more than any other input.
For comparison, a 30-year-old woman at 65 kg and 165 cm has a BMR of 1,370 and a moderate-activity TDEE of 2,124.
Using the number
Once you have a TDEE, the targets follow from it directly.
- To maintain — eat at your TDEE.
- To lose weight — subtract about 500 calories a day, which corresponds to roughly half a kilogram or one pound a week.
- To gain weight — add about 300 calories a day. A smaller surplus than deficit is deliberate: it favours lean tissue over fat.
The 500-calorie figure comes from the rough approximation that a kilogram of body fat represents about 7,700 calories. It is a serviceable planning number rather than a physical constant, and real results vary with water retention, glycogen, hormones and how carefully intake is actually tracked.
Do not go below roughly 1,200 calories a day without medical supervision. Very low intakes make it hard to meet basic nutritional requirements and tend to cost lean tissue rather than fat.
Why estimates drift from reality
The activity multiplier is a guess
This is where nearly all the error lives. Most people place themselves a level too high — three gym sessions a week alongside a desk job is closer to light than moderate for many. Since the multipliers differ by roughly 15% each, one level of optimism is around 250 to 300 calories a day.
Body composition is invisible to the formula
Mifflin-St Jeor uses height, weight, age and sex, so it cannot see how much of your weight is muscle. Muscle is metabolically more expensive than fat, so a lean, muscular person burns more than the equation predicts and a person with higher body fat burns somewhat less.
Your body adapts
Sustained dieting reduces expenditure by more than the weight loss alone accounts for — you fidget less, move less, and the body becomes somewhat more efficient. This is why weight loss slows even when intake has not changed, and why recalculating periodically matters.
Tracking intake is harder than it looks
Studies consistently find people underestimate what they eat, sometimes by several hundred calories a day. Cooking oils, drinks, sauces and portion-size drift are the usual culprits. If the scale is not moving, the intake figure is more often at fault than the TDEE figure.
How to use it in practice
Treat the calculated number as a hypothesis, not a fact. Eat at that level for two to three weeks, weighing yourself under consistent conditions, and watch the trend rather than any single day. If your weight is stable, the estimate was good. If it is moving when you intended it not to, adjust by 100 to 200 calories and observe again.
After a few weeks of real data, your own numbers beat any equation.
Common mistakes
- Overstating activity. The most frequent and most costly error.
- Counting exercise twice — once in the multiplier and again by eating back calories a fitness tracker reports.
- Never recalculating. TDEE falls as you lose weight; a figure from 10 kg ago is too high.
- Chasing an aggressive deficit. Large cuts are harder to hold and cost more muscle than a moderate one.
- Trusting fitness tracker calorie burns. Their accuracy for energy expenditure is generally poor.
This calculator is an educational tool and does not provide medical or dietary advice. Speak to a doctor or a registered dietitian before making significant changes to your diet, particularly if you have any medical condition, are pregnant or breastfeeding, or have a history of disordered eating.
Frequently asked questions
What is TDEE?
Total Daily Energy Expenditure is the number of calories your body uses across a whole day, including everything from keeping you alive at rest through to digesting food and moving around. Eating roughly that number keeps your weight stable.
What is the difference between BMR and TDEE?
BMR is what you would burn lying still all day doing nothing – the cost of running your organs, brain and body temperature. TDEE is BMR multiplied by an activity factor to account for everything you actually do. TDEE is always the larger number.
Which formula does this calculator use?
The Mifflin-St Jeor equation, published in 1990. For men it is (10 x weight in kg) + (6.25 x height in cm) – (5 x age) + 5, and for women the same with -161 in place of +5. It is generally considered the most accurate of the widely used predictive equations.
How accurate is a TDEE estimate?
It is an estimate, not a measurement. Predictive equations typically land within about 10% of measured expenditure for most people, which on a 2,500 calorie day is a spread of roughly 250 calories. Use it as a starting point and adjust based on what actually happens to your weight.
How many calories should I eat to lose weight?
A deficit of about 500 calories a day below your TDEE corresponds to roughly half a kilogram, or about one pound, of weight loss a week. Larger deficits are harder to sustain and cost more lean tissue. Do not drop below roughly 1,200 calories a day without medical supervision.
Which activity level should I pick?
Most people overestimate. Sedentary means a desk job and little deliberate exercise. Moderate means genuine training three to five days a week. If your weight is not moving as the calculator predicts after a few weeks, the activity multiplier is usually the thing that was wrong.
Does TDEE change over time?
Yes. It falls as you lose weight, because a smaller body costs less to run and to move. It also drifts down with age as muscle mass declines. Recalculate every few kilograms of change rather than working from a figure you generated months ago.
Why does the calculator ask for sex at birth?
Because the Mifflin-St Jeor equation was derived with a constant that differs by sex, reflecting average differences in lean body mass. It is a statistical adjustment within the formula, not a judgement, and it is why the male and female versions differ by 166 calories at identical height, weight and age.