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BMR & TDEE Calculator

Find the calories your body burns at rest and across your whole day, with daily targets for losing, maintaining or gaining weight.

BMR Calculator

Be honest here - this multiplier moves the answer more than anything else on the form.

Only if you have measured it. Enables the Katch-McArdle equation, which uses lean mass.

Daily calories to maintain (TDEE)

2,759 kcal

BMR 1,780 kcal × 1.55 for moderately active

BMR

1,780

At complete rest

TDEE

2,759

With your activity

Harris-Benedict

1,854

Older equation

Katch-McArdle

-

Add body fat %

Daily calories by goal

A kilogram of fat stores roughly 7,700 kcal, so a 550 kcal daily deficit is about half a kilo a week.

  • Lose 1 kg / weekAggressive deficit1,659 kcal
  • Lose 0.5 kg / weekSteady deficit2,209 kcal
  • MaintainCurrent weight2,759 kcal
  • Gain 0.25 kg / weekLean gain3,034 kcal
  • Gain 0.5 kg / weekFaster gain3,309 kcal

These are population estimates. Individual metabolic rate varies by roughly 10% either side for reasons no equation can see, so treat this as a starting point: eat at the maintenance figure for two or three weeks, track your weight, and adjust from what actually happens rather than from the number.

The link carries the values you entered, so whoever opens it sees the same result. Nothing is stored on our side — the numbers travel in the link itself.

How the bmr calculation works

Basal metabolic rate is the energy your body uses doing nothing at all — breathing, circulating blood, maintaining temperature, repairing tissue. It accounts for 60% to 75% of most people's daily expenditure, which is why it is the foundation of any calorie target.

The equation

This calculator uses Mifflin-St Jeor, published in 1990 and still the best-supported estimate:

  • Men: BMR = 10w + 6.25h − 5a + 5
  • Women: BMR = 10w + 6.25h − 5a − 161

with weight in kg, height in cm, age in years. For an 80 kg, 180 cm, 30-year-old man: 800 + 1,125 − 150 + 5 = 1,780 kcal a day at complete rest.

It replaced the older Harris-Benedict equation, which tends to read a few percent high — the direction that matters most when someone is eating to a deficit. Both are shown above.

Katch-McArdle uses lean body mass instead of height and sex: 370 + 21.6 × lean kg. It is the most accurate of the three if your body fat percentage is real, and the least accurate if it was guessed — which is why it only appears once you supply a measured figure.

From BMR to TDEE

Total daily energy expenditure multiplies BMR by an activity factor:

Level Factor Meaning
Sedentary 1.2 Desk job, little exercise
Lightly active 1.375 Light exercise 1–3 days
Moderately active 1.55 Moderate exercise 3–5 days
Very active 1.725 Hard exercise 6–7 days
Extremely active 1.9 Physical job or twice-daily training

This multiplier moves the answer more than anything else on the form — the gap between sedentary and very active is over 900 calories for the same person. Most people overestimate. If you have a desk job and train four times a week, you are "moderately active", not "very active".

Calorie targets

A kilogram of body fat stores roughly 7,700 kcal, so a 550 kcal daily deficit is about half a kilo a week. The targets above are built from that arithmetic.

Two cautions. Deficits below about 1,200 kcal for women or 1,500 for men are difficult to meet nutritional needs on and are generally not advised without medical supervision. And a larger deficit is not proportionally better — beyond roughly 25% below maintenance, more of the loss comes from muscle, and adherence collapses.

Why the number is a starting point

Individual metabolic rate varies by around 10% either side of any equation's prediction, for reasons involving thyroid function, body composition, genetics and non-exercise activity. Two people matching on every input can differ by 300 calories a day.

The reliable method is empirical: eat at the predicted maintenance figure for two to three weeks, track weight and the trend rather than daily fluctuation, then adjust by 100–200 calories based on what actually happened. The equation gets you to a sensible starting point; your own data does the rest.

Disclaimer: This calculator provides estimates for general information only and is not medical advice. It cannot account for your medical history, body composition, or individual needs. Talk to a doctor or registered dietitian before making changes to your diet or exercise.

Frequently asked questions

What is the difference between BMR and TDEE?

BMR is what your body burns at complete rest - breathing, circulation, temperature, tissue repair - and accounts for 60% to 75% of daily expenditure. TDEE is BMR multiplied by an activity factor to cover everything else you do. TDEE is the figure to eat at to maintain weight; BMR is a floor you should not be eating below.

Which BMR formula is most accurate?

Mifflin-St Jeor for most people, which is why it is the default here. Harris-Benedict tends to read a few percent high, which matters when eating to a deficit. Katch-McArdle is the most accurate of the three if you have a genuinely measured body fat percentage, since it works from lean mass - but it is the least accurate if that figure was estimated.

How do I know which activity level to pick?

Most people choose one level too high. Sedentary means a desk job and no structured exercise. Moderately active means training three to five times a week - that describes most regular gym-goers. Very active means hard training six or seven days, or a physically demanding job. The gap between sedentary and very active is over 900 calories for the same person, so this choice matters more than any other input.

How many calories should I eat to lose weight?

A deficit of about 550 calories a day from your TDEE gives roughly half a kilogram of loss a week, since a kilogram of fat stores around 7,700 calories. Larger deficits are not proportionally better - beyond roughly 25% below maintenance, more of the loss comes from muscle and adherence tends to collapse. Sustainable beats fast almost every time.

Why is my actual weight loss different from what this predicts?

Individual metabolic rate varies by roughly 10% either side of any equation, and self-reported food intake is typically underestimated by a substantial margin. Weight also fluctuates with water, sodium and glycogen, which can mask real fat loss for weeks. Track the trend over three to four weeks rather than day to day, then adjust intake by 100 to 200 calories based on what actually happened.

Does BMR fall as you lose weight?

Yes, for two reasons. A smaller body costs less to maintain, so BMR falls simply because weight fell. There is also adaptive thermogenesis - a modest additional reduction beyond what the size change predicts, which is real but smaller than commonly claimed. Recalculate every 5 to 10 kg of loss rather than holding the original target for the whole journey.

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