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BMR Calculator: Your Calorie Burn at Rest

In short: Your basal metabolic rate (BMR) is the energy your body burns at complete rest. A woman weighing 68 kg at 1.68 m lands at roughly 1,250 to 1,450 kcal per day depending on age, a man weighing 80 kg at 1.80 m at roughly 1,600 to 1,800 kcal.

Calculate your BMR here using the Mifflin-St Jeor equation, with the revised Harris-Benedict equation as a comparison value. Free, no sign-up, everything runs directly in your browser.

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All values are estimates based on established formulas, not medical or dietetic advice. If you have a medical condition, are pregnant or have an eating disorder, decisions about your energy intake belong in the hands of a doctor or therapist.

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What is the basal metabolic rate?

The basal metabolic rate (BMR) is the amount of calories your body burns at complete rest: for breathing, heartbeat, brain, organs and maintaining body temperature. For most people it makes up the largest share of daily energy expenditure, often 60 to 70 percent.

How the BMR calculator works

As its main result, the calculator uses the Mifflin-St Jeor equation (1990), which performs best in comparison studies of healthy adults:

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

For context, you also see the revised Harris-Benedict equation (Roza and Shizgal, 1984):

  • Men: 88.362 + 13.397 × weight (kg) + 4.799 × height (cm) − 5.677 × age
  • Women: 447.593 + 9.247 × weight (kg) + 3.098 × height (cm) − 4.330 × age

If you know your body fat percentage, for example from a measurement, the calculator additionally applies the Katch-McArdle formula: 370 + 21.6 × lean body mass (kg), where lean body mass is your weight minus fat mass. Because it works with fat-free mass, it can be more accurate when your body fat percentage is known, especially for very muscular or very lean people. You can estimate your body fat percentage with the body fat calculator.

BMR examples using Mifflin-St Jeor

PersonExample valuesAgeBMR
Woman1.68 m, 68 kg25 years1,444 kcal/day
Woman1.68 m, 68 kg45 years1,344 kcal/day
Woman1.68 m, 68 kg65 years1,244 kcal/day
Man1.80 m, 80 kg25 years1,805 kcal/day
Man1.80 m, 80 kg45 years1,705 kcal/day
Man1.80 m, 80 kg65 years1,605 kcal/day

What determines your BMR?

The biggest levers are body weight, height, age and sex, exactly the values used in the formulas. Behind them stands, above all, muscle mass: muscles burn considerably more energy at rest than fat tissue. That is why muscular people have a higher BMR at the same weight, and why BMR declines with age as muscle mass is lost. Strength training and sufficient protein intake counteract this. The protein calculator shows you how much protein fits your situation.

BMR or total daily energy expenditure?

Your BMR only describes what you burn at rest. As soon as you get up, work or exercise, activity energy expenditure comes on top. Together they make up your total daily energy expenditure, your actual daily calorie needs. For the question of how much you should eat, total energy expenditure is the relevant figure. You can work it out with the calorie calculator, which multiplies your BMR by your activity factor.

Why you should not permanently eat below your BMR

Your BMR is the amount of energy your body budgets for its basic functions. If your intake stays well below it for a long time, the body responds with savings programs: it reduces spontaneous everyday movement, breaks down muscle mass alongside fat and lowers its energy use even further. Weight loss stalls even though you are eating very little, and it becomes hard to get enough protein, vitamins and minerals. For sustainable weight loss, a moderate deficit of about 300 to 500 kcal below your total energy expenditure has proven itself, with your BMR as the lower guardrail.

Frequently asked questions about BMR

What is a normal basal metabolic rate?

It depends mainly on weight, height, age and sex. Using the Mifflin-St Jeor equation, a woman weighing 68 kg at 1.68 m lands at roughly 1,250 to 1,450 kcal per day depending on age, a man weighing 80 kg at 1.80 m at roughly 1,600 to 1,800 kcal. Taller, heavier and more muscular people come in above these figures, smaller and older people below them.

BMR or total daily energy expenditure, which one matters for weight loss?

Total daily energy expenditure. On top of your BMR, it includes the energy you use for movement, work and exercise, which makes it the reference point for your calorie deficit. Your BMR serves more as a lower guardrail: permanently eating less than your body burns at complete rest is not a sensible strategy.

Why is my BMR so low?

It usually comes down to the input values: with lower weight, smaller height and higher age, the calculated BMR drops. Low muscle mass also reduces resting energy expenditure, because muscles burn energy even at rest. On top of that, the body adapts to long, strict diets and dials its energy use down somewhat.

Does building muscle increase your BMR?

Yes. Muscle tissue burns energy even at rest, considerably more than fat tissue. If you build muscle over months, you raise your BMR along the way. The effect per kilogram of muscle mass is modest, but combined with the training itself, strength training makes a noticeable difference to your energy balance.

Which formula is the most accurate?

In comparison studies, the Mifflin-St Jeor equation from 1990 performs best in healthy adults, which is why it is the main result here. The revised Harris-Benedict equation provides a second reference point. If you know your body fat percentage, the Katch-McArdle formula can be more accurate, because it works with your lean body mass.

What happens if I permanently eat below my BMR?

The body saves energy wherever it can: it reduces everyday movement, breaks down muscle mass alongside fat and lowers its energy use as a result. Weight loss stalls even though you are eating very little, and your supply of protein, vitamins and minerals runs short. A moderate deficit below your total energy expenditure, but above your BMR, is the more sensible approach.

Can I have my BMR measured?

Yes, with indirect calorimetry: a breathing mask measures how much oxygen you consume and how much carbon dioxide you exhale. Some medical practices, performance diagnostics centers and nutrition counseling services offer these measurements. For everyday purposes, the formula-based estimate is usually a good enough starting point.

Sources

  • Mifflin MD, St Jeor ST et al.: A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition 1990; 51(2): 241-247. PubMed 2305711
  • Roza AM, Shizgal HM: The Harris Benedict equation reevaluated: resting energy requirements and the body cell mass. American Journal of Clinical Nutrition 1984; 40(1): 168-182. PubMed 6741850
  • Frankenfield D, Roth-Yousey L, Compher C: Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults. Journal of the American Dietetic Association 2005; 105(5): 775-789.
  • Katch FI, McArdle WD: Nutrition, Weight Control, and Exercise. Lea & Febiger, Philadelphia (Katch-McArdle formula based on fat-free mass).