BMR Calculator: How Many Calories Do You Burn at Rest?
A 30-year-old male, 5'10", 175 lbs has a BMR of approximately 1,765 calories per day. This means his body burns 1,765 calories just to maintain basic life functions — breathing, circulation, cell production — even with zero physical activity. BMR typically accounts for 60-75% of total daily cal...
Calculate Your BMR
Your body's calorie burn at complete rest.
Your BMR
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calories/day at rest
The Mifflin-St Jeor Equation
Men: BMR = (10 x weight in kg) + (6.25 x height in cm) - (5 x age) + 5 Women: BMR = (10 x weight in kg) + (6.25 x height in cm) - (5 x age) - 161
BMR by Age and Gender (Sample Values)
| Age | Male (5'10", 175 lbs) | Female (5'5", 145 lbs) |
|---|---|---|
| 20 | 1,815 cal/day | 1,413 cal/day |
| 30 | 1,765 cal/day | 1,363 cal/day |
| 40 | 1,715 cal/day | 1,313 cal/day |
| 50 | 1,665 cal/day | 1,263 cal/day |
| 60 | 1,615 cal/day | 1,213 cal/day |
Factors That Affect BMR
Muscle mass is the biggest controllable factor. Muscle tissue burns 6 calories per pound per day at rest, compared to 2 calories per pound for fat. This is why strength training is valuable for weight management — building 5 lbs of muscle increases your daily resting calorie burn by about 20 calories.
Other factors: Genetics, thyroid function, hormonal balance, ambient temperature, caffeine intake, and recent meal timing all influence BMR. Crash diets can suppress BMR by 15-20% through metabolic adaptation, which is why extreme calorie restriction often backfires long-term.
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. doi:10.1093/ajcn/51.2.241
2. Harris JA, Benedict FG. A Biometric Study of Human Basal Metabolism. Proc Natl Acad Sci USA. 1918;4(12):370-373. doi:10.1073/pnas.4.12.370
3. Frankenfield D, Roth-Yousey L, Compher C. Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults. J Am Diet Assoc. 2005;105(5):775-789. doi:10.1016/j.jada.2005.02.005
Frequently Asked Questions
What is BMR?
BMR (Basal Metabolic Rate) is the minimum number of calories your body needs to maintain basic physiological functions at complete rest — breathing, circulation, cell repair, and organ function. It is measured under strict resting conditions: 12 hours of fasting, 8 hours of sleep, and a thermoneutral environment.
What is the difference between BMR and RMR?
BMR (Basal Metabolic Rate) and RMR (Resting Metabolic Rate) are very similar but measured under slightly different conditions. BMR requires complete rest after overnight fasting in a clinical setting. RMR is measured under less restrictive conditions and tends to be 10-20% higher than BMR. For practical purposes, most calculators (including this one) estimate RMR but call it BMR.
Can I increase my BMR?
Yes. Building lean muscle mass through resistance training is the most effective way to increase BMR. Each pound of muscle burns approximately 6 calories per day at rest. Other factors include staying hydrated, getting adequate sleep (7-9 hours), managing stress, and avoiding extreme calorie restriction which lowers BMR.
Why does BMR decrease with age?
BMR decreases approximately 1-2% per decade after age 20, primarily due to loss of lean muscle mass (sarcopenia) and hormonal changes. A 2021 study in Science showed the decline is less dramatic than previously thought — only about 0.7% per year from 20 to 60. Maintaining muscle mass through resistance training can significantly offset this decline.
Is the Mifflin-St Jeor equation the best BMR formula?
The Mifflin-St Jeor equation is considered the most accurate for the general population. A 2005 systematic review by Frankenfield et al. in the Journal of the American Dietetic Association found it was the most reliable predictor of BMR, outperforming the Harris-Benedict (1919) and WHO/FAO equations. The Katch-McArdle formula may be more accurate for lean, athletic individuals if body fat percentage is known.