BMR Calculator
Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest to maintain basic functions — breathing, circulation, cell repair, and temperature regulation. It accounts for 60–70% of total daily energy expenditure for most people.
Tip: Muscle tissue burns roughly 6 kcal/lb per day at rest, compared to only 2 kcal/lb for fat tissue. Building muscle permanently raises your BMR.
- 1Use the Mifflin-St Jeor equation (most accurate for most adults)
- 2Men: BMR = 10×weight(kg) + 6.25×height(cm) − 5×age + 5
- 3Women: BMR = 10×weight(kg) + 6.25×height(cm) − 5×age − 161
- 4Multiply BMR by an activity factor to get Total Daily Energy Expenditure (TDEE)
- 5Adjust TDEE by ±500 kcal/day for ~0.5 kg/week weight change
Mifflin vs Harris-Benedict
The Harris-Benedict equation (1919) was the original standard. The Mifflin-St Jeor equation (1990) is more accurate for modern populations, with an average error of ±10%.
Adaptive thermogenesis
Long-term caloric restriction lowers BMR as the body adapts. This is why weight loss plateaus occur — the body becomes more efficient at lower calorie intakes.
| Activity Level | Multiplier | Description |
|---|---|---|
| Sedentary | 1.2 | Desk job, little or no exercise |
| Lightly active | 1.375 | Light exercise 1–3 days/week |
| Moderately active | 1.55 | Moderate exercise 3–5 days/week |
| Very active | 1.725 | Hard exercise 6–7 days/week |
| Extra active | 1.9 | Very hard exercise + physical job |
Fun Fact
Your brain alone consumes about 20% of your BMR despite being only 2% of your body weight.