BMR Calculator
Calculate your Basal Metabolic Rate and discover exactly how many calories your body needs each day at every activity level — powered by the Mifflin-St Jeor equation.
What Is BMR?
Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest to sustain essential physiological functions — including breathing, blood circulation, cell repair, hormone production, and temperature regulation. Think of it as the energy your body would need if you stayed in bed all day without moving.
BMR typically accounts for 60–75% of total daily calorie expenditure for sedentary individuals. Understanding your BMR gives you the foundation for setting any nutrition goal — whether you want to lose fat, build muscle, or simply maintain your current weight.
The Mifflin-St Jeor Equation
This calculator uses the Mifflin-St Jeor equation (1990), widely regarded as the most accurate BMR formula for general use:
For men:
BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) + 5
For women:
BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) − 161
Activity Level Multipliers (TDEE)
| Activity Level | Description | Multiplier |
|---|---|---|
| Sedentary | Little to no exercise, desk job | × 1.2 |
| Lightly active | Light exercise 1–3 days/week | × 1.375 |
| Moderately active | Moderate exercise 3–5 days/week | × 1.55 |
| Very active | Hard exercise 6–7 days/week | × 1.725 |
| Extra active | Very hard exercise or physical job | × 1.9 |
Frequently Asked Questions
What is BMR?▼
BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest to sustain vital functions — breathing, circulation, cell production, and temperature regulation. It represents the minimum caloric intake needed to keep you alive.
What formula does this BMR calculator use?▼
This calculator uses the Mifflin-St Jeor equation, published in 1990 and validated as the most accurate BMR formula for most adults. It accounts for weight, height, age, and biological sex.
What is the difference between BMR and TDEE?▼
BMR is calories burned at complete rest. TDEE (Total Daily Energy Expenditure) multiplies BMR by an activity factor to account for movement, exercise, and daily tasks. TDEE is what you actually need to maintain your current weight.
How accurate is a BMR calculator?▼
The Mifflin-St Jeor equation is accurate to within ±10% for most adults. Accuracy decreases for very high muscle mass or extreme obesity. Consult a registered dietitian for clinical precision.
How many calories should I eat to lose weight?▼
A commonly recommended deficit is 500 calories per day below your TDEE, which typically produces roughly 0.5 kg (1 lb) of weekly weight loss. Never eat below your BMR without medical supervision.