BMR
Definition
Basal Metabolic Rate — the number of calories your body requires at complete rest to maintain basic life-sustaining functions like breathing, circulation, cell production, and organ function. BMR accounts for 60–75% of your total daily calorie expenditure. The most accurate BMR formula is the Mifflin-St Jeor equation: for men, BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5; for women, BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161. Factors that increase BMR include higher muscle mass, younger age, male sex, and taller height.
Why is BMR Important?
Understanding BMR empowers you to take control of your personal health and wellness. Whether you are tracking body composition, planning nutrition, or evaluating fitness metrics, this concept provides the foundation for making informed health decisions backed by science.
Our health calculators make these metrics accessible and easy to compute, giving you instant, evidence-based results so you can focus on achieving your wellness goals rather than crunching numbers.
What is BMR?
Basal Metabolic Rate (BMR) is the number of calories your body needs per day at complete rest to maintain basic life-sustaining functions — breathing, blood circulation, cell production, brain function, and body temperature regulation. BMR represents the largest portion (60–70%) of your total daily calorie expenditure.
BMR Formulas
Mifflin-St Jeor (Most Accurate — Recommended)
| Sex | Formula |
|---|---|
| Men | BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) + 5 |
| Women | BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) − 161 |
Harris-Benedict (Original, Slightly Less Accurate)
| Sex | Formula |
|---|---|
| Men | BMR = 88.362 + (13.397 × kg) + (4.799 × cm) − (5.677 × age) |
| Women | BMR = 447.593 + (9.247 × kg) + (3.098 × cm) − (4.330 × age) |
BMR by Age and Sex (Average)
| Age | Male (avg build) | Female (avg build) |
|---|---|---|
| 20–29 | 1,700–1,900 cal | 1,350–1,500 cal |
| 30–39 | 1,650–1,850 cal | 1,300–1,450 cal |
| 40–49 | 1,600–1,800 cal | 1,250–1,400 cal |
| 50–59 | 1,550–1,750 cal | 1,200–1,350 cal |
| 60+ | 1,400–1,650 cal | 1,100–1,300 cal |
Factors That Affect BMR
| Factor | Effect |
|---|---|
| Muscle mass | More muscle = higher BMR (muscle burns ~6 cal/lb/day at rest vs fat at ~2 cal/lb/day) |
| Body size | Larger bodies burn more at rest |
| Age | BMR decreases ~1–2% per decade after age 20 |
| Sex | Males have ~5–10% higher BMR than females (more muscle mass on average) |
| Genetics | Can cause up to ±200 cal variation between individuals of same size/age |
| Thyroid function | Overactive thyroid increases BMR; underactive decreases it |
| Crash dieting | Severe caloric restriction can lower BMR by 15–20% (metabolic adaptation) |