BMR calculator: the energy your body uses at rest
Enter your age, sex, weight and height to estimate the energy your body uses at complete rest over a day. This is the minimum for your organs to work, not how much you should eat.
What the result means
BMR (basal metabolic rate) is the energy your body uses to keep its organs working at complete rest: breathing, heartbeat, body temperature and so on. It is usually the largest share of daily energy use.
The equation used (Mifflin-St Jeor) actually estimates resting energy expenditure (REE), which is measured under slightly less strict conditions than BMR. We use the familiar term BMR, but the value is an equation-based estimate, not a direct measurement.
BMR is not a calorie target, because it excludes the energy used for movement and digestion. Eating below your BMR for long periods is not something this tool recommends.
How it is calculated
- Mifflin-St Jeor equation: Male = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5 · Female = 10 × weight + 6.25 × height − 5 × age − 161
- The original abstract (Mifflin et al. 1990) gives a combined form 9.99 × weight + 6.25 × height − 4.92 × age + 166 × sex (male 1, female 0) − 161; this tool uses the rounded sex-specific form used by MSD Manuals, which differs by only a few kcal
- Results are rounded to the nearest 10 kcal; pounds/inches are converted first per NIST SP 811
Limitations and cautions
- The equation was derived from 498 healthy adults aged 19–78; individual values may differ, especially for people with more or less muscle than typical
- Not for pregnancy or breastfeeding, and not suitable if you have a condition or take medicines that affect energy use
- This tool does not set a personal energy target
Results are estimates or basic screening only, not a medical diagnosis or medical advice.
Related articles
- Does a slow metabolism cause weight gain? Facts about how you burn energy ›
- What is a calorie deficit? Eating less energy than you use, in a way you can keep up ›
Related tools
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References
- Mifflin MD, St Jeor ST, et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr 1990;51:241–247 ↗ (opens in a new tab)
- MSD Manuals: Mifflin-St Jeor Equation medical calculator (checked 9 Oct 2026) ↗ (opens in a new tab)
- NIST SP 811 Appendix B.8 — unit conversion factors ↗ (opens in a new tab)
Compiled by Well Nutrition Hub from the sources listed. Content last reviewed 16 Oct 2026.