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BMR Calculator

Find how many calories your body burns at complete rest. See your BMR per day and per hour, compare three formulas, then add your activity to get your daily calories.

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Your basal metabolic rate (Mifflin-St Jeor)
—calories / day
—
Calories per hour at rest
—
Calories per week at rest
—
Harris-Benedict
—
Mifflin-St Jeor
—
Katch-McArdle

BMR is what you burn at rest. Your daily calories add your activity on top. Now add your activity: open the TDEE calculator

From BMR to daily calories

Your BMR multiplied by each activity factor gives your TDEE (maintenance calories).

ActivityFactorCalories / day
Written by Updated Sources listed at the end

What BMR means

Basal metabolic rate (BMR) is the energy your body needs to stay alive at complete rest: breathing, circulation, keeping warm and running your organs. For most people it is the largest part of daily energy use, roughly 60–70%. For a plain-language definition, see What does BMR mean?

The three formulas

Mifflin-St Jeor: 10 × kg + 6.25 × cm − 5 × age + 5 (men) or − 161 (women)
Revised Harris-Benedict, men: 88.362 + 13.397 × kg + 4.799 × cm − 5.677 × age
Revised Harris-Benedict, women: 447.593 + 9.247 × kg + 3.098 × cm − 4.330 × age
Katch-McArdle: 370 + 21.6 × lean body mass (kg)

A 2005 systematic review found Mifflin-St Jeor estimated resting metabolic rate within 10% of measured values in more people than other common equations, so it is the default here. Katch-McArdle can suit very lean or muscular people who know their body fat. Which formula should you use? compares them for three different people.

Worked example

30-year-old woman, 65 kg, 165 cm10 × 65 = 650; 6.25 × 165 = 1,031.25; 5 × 30 = 150. 650 + 1,031.25 − 150 − 161 = 1,370 calories a day, or about 57 calories an hour. Harris-Benedict gives 1,430 for the same woman.

What changes your BMR

  • Body size. A bigger body uses more energy to run.
  • Muscle. Lean tissue uses more energy at rest than fat.
  • Age. For the same 80 kg, 178 cm man, Mifflin-St Jeor gives 1,768 at age 30 and 1,618 at 60.
  • Sex. Men tend to have more lean mass at the same weight.
  • Weight loss. BMR falls as you get lighter, which is one reason progress slows. See why your TDEE drops.

From BMR to calories

BMR alone is not a diet target. Multiply it by your activity factor to get TDEE, then set a goal from there. The table above does the multiplication; the TDEE calculator adds goals and macros. TDEE vs BMR explains the difference in depth.

Related

What does BMR mean?A plain definition.TDEE calculatorAdd activity, goals and macros.Katch-McArdle calculatorBMR from lean mass.

Sources

  1. Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990;51(2):241–247. PubMed 2305711
  2. Roza AM, Shizgal HM. The Harris Benedict equation reevaluated: resting energy requirements and the body cell mass. Am J Clin Nutr. 1984;40(1):168–182. PubMed 6741850
  3. Frankenfield D, Roth-Yousey L, Compher C. Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review. J Am Diet Assoc. 2005;105(5):775–789. PubMed 15883556

Frequently asked questions

How do I calculate my BMR?
Use the Mifflin-St Jeor equation: 10 × weight (kg) + 6.25 × height (cm) − 5 × age, then add 5 for men or subtract 161 for women. This calculator does it for you and compares it with Harris-Benedict and, if you add body fat, Katch-McArdle.
What is a normal BMR?
There is no single normal value. BMR depends on size, muscle, age and sex. Many adult women fall roughly between 1,200 and 1,600 calories a day and many men between 1,500 and 2,000, but larger or more muscular people sit higher.
Is BMR the same as the calories I need?
No. BMR is only what you burn at complete rest. Your daily needs (TDEE) add digestion and all your movement, usually 20% to 90% more. Use the TDEE calculator for your full daily number.
Does BMR go down with age?
Yes, slowly. In the Mifflin-St Jeor equation, BMR falls by 5 calories a day for every year of age. Much of the real-world drop comes from losing muscle, which strength training helps limit.
Should I eat less than my BMR to lose weight?
Most people do not need to. Set your target from TDEE minus 250–500 calories. Eating below BMR usually means a very large deficit, which is hard to sustain and makes it harder to keep muscle.