BMR & TDEE Calculator

Built by Puja Matharu, Australian Certified Nutritionist Updated 2026-07-30 Free, and nothing you enter leaves your browser

How this is calculated

This calculator uses the Mifflin-St Jeor equation, which is the most accurate of the widely used predictive formulas for resting metabolic rate in the general population.

BMR (men) = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5

BMR (women) = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161

Your BMR is what you'd burn lying still all day — the cost of keeping your organs running. Your TDEE (total daily energy expenditure) is BMR multiplied by an activity factor:

Activity level	Multiplier
Sedentary — desk job, little exercise	1.2
Light — 1–2 sessions a week	1.375
Moderate — 3–5 sessions a week	1.55
Active — 6–7 sessions a week	1.725
Very active — physical job or twice-daily training	1.9

The weight-loss figure applies a 15% reduction and the muscle-gain figure a 10% increase — deliberately modest, because larger deficits accelerate muscle loss and metabolic adaptation without speeding fat loss proportionally.

How accurate is it, really?

Predictive equations estimate a population average for your inputs. Individual resting metabolic rate can vary by roughly 10% in either direction from the prediction, and the activity multiplier is the larger source of error — most people overestimate their own activity level.

Treat the output as a starting point, not a measurement. The reliable method is to eat at the estimate for two to three weeks, track your weekly average weight, and adjust from what actually happened. That real-world feedback beats any equation.

Choose one level lower than you think. The multipliers account for all daily movement, not just formal exercise. Someone who trains four times a week but sits at a desk the other twenty-three hours is closer to "light" than "moderate".

Why your number drops as you lose weight

A lighter body costs less to run. Losing 10 kg can reduce daily expenditure by roughly 200–300 calories, which means the deficit that was working slowly closes on its own. This is the main reason progress stalls, and it's covered in why your weight loss stopped.

Once you have your calorie target, the macro calculator splits it into protein, carbohydrate and fat.

Frequently asked questions

What is the difference between BMR and TDEE?

BMR, basal metabolic rate, is what your body burns at complete rest just keeping your organs running. TDEE, total daily energy expenditure, is BMR multiplied by an activity factor to account for movement, exercise and digestion. TDEE is the number that matters for setting calorie targets.

How accurate is the Mifflin-St Jeor equation?

It is the most accurate of the widely used predictive formulas, but individual resting metabolic rate can vary by roughly 10 percent either side of the prediction. The activity multiplier is the larger source of error, because most people overestimate their activity level. Treat the result as a starting point and adjust based on two to three weeks of real-world weight data.

Which activity level should I choose?

Usually one level lower than you think. The multipliers account for all daily movement, not just formal exercise, so someone who trains four times a week but sits at a desk the rest of the time is closer to 'light' than 'moderate'.

Why does my calorie target drop as I lose weight?

A lighter body costs less energy to run. Losing 10 kg can reduce daily energy expenditure by roughly 200 to 300 calories, which means the deficit that was working slowly closes on its own. This is a common reason weight loss stalls.

References

A number is a starting point, not a plan

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General nutrition information only — not medical advice, diagnosis or treatment. See our health disclaimer.