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Estimate Basal Metabolic Rate using the Mifflin-St Jeor equation by sex, age, weight and height — the resting kcal/day baseline for diet planning.
Health
Generated on May 23, 2026
Estimate Basal Metabolic Rate using the Mifflin-St Jeor equation by sex, age, weight and height — the resting kcal/day baseline for diet planning.
Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest to maintain basic life-sustaining functions — breathing, circulation, cell repair, temperature regulation, and organ function. It represents 60–75% of your total daily calorie expenditure, making it the foundation of any weight-management or performance-nutrition plan. Knowing your BMR allows you to build accurate calorie goals — whether for fat loss, muscle gain, or maintenance — rather than relying on generic recommendations that do not account for your weight, height, age, and sex.
Formula
Mifflin–St Jeor equation. Men: BMR = 10W + 6.25H − 5A + 5. Women: BMR = 10W + 6.25H − 5A − 161. (W = weight in kg, H = height in cm, A = age in years)If you've ever been told to eat 1,800 calories and felt ravenous by 3 PM, the problem usually isn't willpower — it's that the number was generic, not yours. BMR (Basal Metabolic Rate) is the calories your body burns just keeping the lights on: heart pumping, lungs breathing, organs running, cells repairing. It's typically 60 to 75 percent of everything you burn in a day, which makes it the foundation every nutrition plan should sit on. Most calorie targets pulled from a women's magazine assume a 'standard adult' of 70 kg. If you're a 55 kg software engineer in Lahore or an 85 kg site supervisor in Dammam, that average is hilariously off for you. The Mifflin-St Jeor equation this calculator uses is what registered dietitians actually use, and it gets within roughly 10 percent of what a lab measurement would give — close enough to plan around. Honest take: BMR is a starting point, not the eating target. Your real daily intake should be BMR multiplied by an activity factor (that's TDEE), and your deficit should sit 300 to 500 below TDEE, never below BMR itself. Eating below BMR for weeks triggers metabolic adaptation, muscle loss, and the rebound that ruins every aggressive diet. Slow is the actually fast route.
Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest to maintain basic life-sustaining functions — breathing, circulation, cell repair, temperature regulation, and organ function. It represents 60–75% of your total daily calorie expenditure, making it the foundation of any weight-management or performance-nutrition plan. Knowing your BMR allows you to build accurate calorie goals — whether for fat loss, muscle gain, or maintenance — rather than relying on generic recommendations that do not account for your weight, height, age, and sex.
The Mifflin–St Jeor equation, published in 1990, is considered the most accurate predictive BMR formula for the general population and is preferred by dietitians worldwide. Weight contributes most (heavier bodies need more baseline energy to sustain); height is secondary (taller people have more surface area and slightly higher BMR); age is inverse (BMR declines with age as muscle mass decreases and organ function slows); sex matters because men typically carry more lean mass, which has a higher metabolic demand than fat tissue.
Approximate daily calories burned at rest for common body profiles. Use our calculator for an exact figure using your inputs.
| Profile | Weight | Height | Age | BMR (kcal/day) |
|---|---|---|---|---|
| Adult Male | 60 kg | 170 cm | 25 | 1,524 |
| Adult Male | 70 kg | 175 cm | 30 | 1,649 |
| Adult Male | 80 kg | 180 cm | 35 | 1,755 |
| Adult Male | 90 kg | 185 cm | 40 | 1,849 |
| Adult Male | 80 kg | 180 cm | 50 | 1,680 |
| Adult Female | 50 kg | 160 cm | 25 | 1,217 |
| Adult Female | 60 kg | 165 cm | 30 | 1,338 |
| Adult Female | 65 kg | 168 cm | 35 | 1,383 |
| Adult Female | 70 kg | 170 cm | 40 | 1,411 |
| Adult Female | 65 kg | 168 cm | 50 | 1,308 |
An average adult BMR (~1,600 kcal/day) is the energy used just to breathe, pump blood, and keep body temperature — equivalent to a 65 W lightbulb running for a day.
BMR drops ~2% per decade after age 20 — the biological basis for why weight gain becomes easier with age.
1 kg of muscle burns ~13 kcal/day at rest; 1 kg of fat burns only ~4 kcal/day — hence strength training's long-term metabolic benefit.
Male BMR averages ~300 kcal/day higher than female BMR at the same age/weight due to higher lean-mass proportion.
A 30-year-old male weighing 75 kg at 178 cm has a BMR of approximately 1,688 kcal/day — his body burns that much just resting.
A 28-year-old female at 60 kg and 165 cm has a BMR around 1,361 kcal/day — notably lower due to sex and lower body mass.
A 50-year-old male at 85 kg and 180 cm has a BMR near 1,730 kcal/day — slightly lower than his 30-year-old self at the same weight.
A 25-year-old female athlete at 55 kg and 170 cm has a BMR of about 1,343 kcal/day, consistent with her lean frame.
As a 40-year-old loses muscle and gains fat over the next decade, his BMR can fall by 100–200 kcal/day — a main reason 'middle-age spread' is so common.
Someone shifting from 70 to 80 kg adds roughly 100 kcal/day to their BMR just from needing to maintain the extra tissue.
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