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Nutrition

BMR calculator

The calories your body burns at rest, using the Mifflin–St Jeor equation.

Your stats

Basal metabolic rate
1,783kcal / day

Calories your body burns at complete rest to keep basic functions running.

BMR does not include any movement or digestion. For your total daily burn, multiply by an activity factor — or use the TDEE calculator.

What is BMR

Your basal metabolic rate is the energy your body needs to stay alive without doing anything. Your heart still beats, your lungs still move, your brain still thinks, and your cells still repair themselves — and all of that costs calories. For an average adult, BMR accounts for roughly two thirds of total daily energy burn.

BMR is influenced mainly by lean body mass (more muscle means a higher BMR), height, age, and sex. It drops slightly with age — roughly 1–2 percent per decade after thirty — largely because muscle mass tends to decline if it is not actively maintained.

How BMR is calculated

This calculator uses the Mifflin–St Jeor equation:

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

The constants come from a 1990 study that compared several equations against indirect calorimetry — the gold-standard method for measuring metabolic rate — and found Mifflin–St Jeor to be the most accurate across body sizes.

Frequently asked questions

What is BMR?
Basal metabolic rate is the number of calories your body burns to keep basic life functions going — breathing, circulating blood, maintaining body temperature, and repairing cells. It is what you would burn if you lay still in bed all day. For most people, BMR makes up 60–70 percent of total daily calorie burn.
What is the difference between BMR and TDEE?
BMR is what you burn at complete rest. TDEE (Total Daily Energy Expenditure) is BMR plus everything else you do — walking, fidgeting, digesting food, training. TDEE is the more useful number for setting a calorie target; BMR is the building block underneath it.
Which equation does this use?
The Mifflin–St Jeor equation, published in 1990. It is recommended by the Academy of Nutrition and Dietetics as the most accurate predictive BMR formula for healthy adults. It is more accurate than the older Harris–Benedict equation, which tends to overestimate.
How accurate is the result?
Predictive equations are usually within about 10 percent of measured BMR. Genetics, muscle mass, and thyroid function all influence true BMR, so treat the number as a reasonable estimate rather than a precise measurement.
Why does muscle matter for BMR?
Muscle tissue is more metabolically active than fat. Two people of the same weight and height will have different true BMRs if one is significantly leaner. The Katch–McArdle formula adjusts for body fat percentage and may give a closer estimate if you have a recent body-fat reading.

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