BMR Calculator
Find how many calories your body burns at complete rest.
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Short answer
Your BMR (basal metabolic rate) is what your body burns at complete rest, just to keep you alive: breathing, circulation, brain and organs. It's most of your daily burn, roughly 60–70%. A 30-year-old man who is 5 ft 10 in and 180 lb has a BMR of about 1,780 calories a day.
The formulas
Mifflin-St Jeor (what we use by default):
- Men: 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5
- Women: 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161
Katch-McArdle (used when you enter body fat): 370 + 21.6 × lean body mass (kg). Because it's based on lean mass, it suits very muscular or very lean people better than height and weight alone.
Harris-Benedict (1919) is still common online. In the study that created Mifflin-St Jeor, it overestimated measured resting burn by about 5%, so we don't use it.
Example
| 30-year-old man, 5 ft 10 in, 180 lb | BMR |
|---|---|
| Mifflin-St Jeor | 1,783 |
| Katch-McArdle at 18% body fat | 1,816 |
Multiply by an activity level to get TDEE. At "Moderate" (1.55), his 1,783 becomes about 2,763 calories a day.
BMR, RMR and TDEE
| Term | Means |
|---|---|
| BMR | Burn at complete rest, measured under strict lab conditions |
| RMR | Resting burn measured in looser conditions; usually a little higher than BMR. Calculators treat them as the same. |
| TDEE | BMR plus movement, exercise and digesting food. This is what you eat to. |
What changes your BMR
- Body size. Bigger bodies burn more, so BMR drops as you lose weight.
- Muscle. Lean mass burns more than fat. Strength training helps you keep it.
- Age and sex. BMR declines slowly with age, and men tend to burn more at the same weight.
How accurate is it?
In a systematic review of the four most-used equations, Mifflin-St Jeor was the most reliable, landing within 10% of measured resting burn for more people than any other. The review also noted bigger errors for some individuals, and that older adults and some ethnic groups were underrepresented in the research. For an exact number, a clinic can measure it with indirect calorimetry.
More calculators
Not medical advice. These numbers are estimates for healthy adults aged 18–80, based on published equations. They aren't reviewed by a doctor or registered dietitian. Talk to one before making big changes to how you eat, especially if you're pregnant or breastfeeding, under 18, have a history of disordered eating, have a medical condition, or take medication that affects appetite or weight. Medical disclaimer
Sources
- Mifflin MD, St Jeor ST, et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr, 1990.
- 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.
You're a 30-year-old man, 5 ft 10 in and 180 lb, moderately active.
You burn about
2,763
calories a day
Likely range 2,490–3,040 · 19,341 a week
This already counts your workouts, so don't add your watch's exercise calories on top.
for a more accurate number.
Your goal
How fast, per week
to lose about 1 lb a week
Daily macros
Protein is set from your body weight. The style changes how the rest splits between carbs and fat.
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Your body
BMI can't tell muscle from fat. If you lift, your waist size says more.
All calorie targets
Calories by activity level
Ideal weight formulas
For lifters: your muscle potential
BMR and formula
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Food scaleThe fastest way to stop under-counting food.View Bathroom scaleWeigh in weekly to check your number is right.View Body fat calipersKnow your body fat % for a sharper estimate.ViewEstimates for healthy adults, typically within 10–15%. Track your weight for 2–3 weeks and adjust by 100–200 calories if needed. Recalculate every 10–20 lb (5–10 kg). Not medical advice.
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