Basal metabolic rate is the number of calories your body burns at complete rest to keep essential functions running — breathing, circulation, cell repair and brain activity. It typically accounts for 60 to 70 percent of the calories you burn each day.

Is BMR different for men and women?

Yes. Unlike BMI, the BMR formula has a genuine sex term. Using Mifflin-St Jeor, a man and a woman of identical weight, height and age differ by exactly 166 calories per day, because men typically carry more lean mass.

Which BMR formula is most accurate?

Mifflin-St Jeor is the current default in clinical and sports nutrition practice, and is generally more accurate for modern populations than the older Harris-Benedict equation. Neither accounts for body composition, so both overestimate for people carrying high body fat and underestimate for very muscular people.

Should I eat my BMR number of calories?

No. BMR is what you would burn lying still all day. Your actual needs are your BMR multiplied by an activity factor, which is your TDEE. Eating at BMR while living a normal life creates a substantial unintended deficit.

BMR Calculator

Basal metabolic rate (BMR) is the number of calories your body burns at complete rest, just to stay alive. It covers breathing, circulation, cell repair and brain activity, and it usually accounts for 60–70% of everything you burn in a day. This calculator uses the Mifflin-St Jeor equation, the current clinical default.

Calculate your BMR

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The Mifflin-St Jeor equation

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

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

The two constants differ by 166 calories. That gap is the entire sex difference in the formula — everything else is identical.

Worked example

A 30-year-old man at 80 kg and 180 cm: (10 × 80) + (6.25 × 180) − (5 × 30) + 5 = 800 + 1125 − 150 + 5 = 1,780 calories per day at rest.

From BMR to daily calories

BMR is not what you should eat. Multiply it by an activity factor to get your total daily energy expenditure — that is the number that matters for planning intake.

Activity multipliers applied to BMR
Activity level	Description	Multiplier
Sedentary	Desk job, little or no exercise	× 1.2
Lightly active	Light exercise 1–3 days a week	× 1.375
Moderately active	Moderate exercise 3–5 days a week	× 1.55
Very active	Hard exercise 6–7 days a week	× 1.725
Extremely active	Physical job or twice-daily training	× 1.9

Use the TDEE calculator to apply these automatically.

Common questions about BMR

What is BMR?: Basal metabolic rate is the number of calories your body burns at complete rest to keep essential functions running — breathing, circulation, cell repair and brain activity. It typically accounts for 60 to 70 percent of the calories you burn each day.
Is BMR different for men and women?: Yes. Unlike BMI, the BMR formula has a genuine sex term. Using Mifflin-St Jeor, a man and a woman of identical weight, height and age differ by exactly 166 calories per day, because men typically carry more lean mass.
Which BMR formula is most accurate?: Mifflin-St Jeor is the current default in clinical and sports nutrition practice, and is generally more accurate for modern populations than the older Harris-Benedict equation. Neither accounts for body composition, so both overestimate for people carrying high body fat and underestimate for very muscular people.
Should I eat my BMR number of calories?: No. BMR is what you would burn lying still all day. Your actual needs are your BMR multiplied by an activity factor, which is your TDEE. Eating at BMR while living a normal life creates a substantial unintended deficit.