Free browser-based tool
BMR Calculator
Calculate your Basal Metabolic Rate (BMR) — the calories your body burns at complete rest — and your Total Daily Energy Expenditure (TDEE) based on activity level. Uses the gold-standard Mifflin-St Jeor equation validated by clinical research.
BMR
1,709
kcal / day at rest
TDEE
2,649
kcal / day total
2,149
Weight loss
−500 kcal/day deficit
2,649
Maintenance
Maintain current weight
2,949
Muscle gain
+300 kcal/day surplus
Based on the Mifflin-St Jeor equation (most accurate for general adult population). Values are estimates; individual variation of ±10% is normal.
What is BMR (Basal Metabolic Rate)?
Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest over 24 hours to maintain essential physiological functions.
Breathing
Respiratory system function
Circulation
Heart pumping blood
Cell Repair
Tissue maintenance
Brain Function
Neural activity
BMR accounts for 60–75% of your total daily energy expenditure in most people. The remaining 25–40% comes from physical activity and food digestion (thermic effect of food).
BMR vs TDEE — What's the Difference?
BMR
Calories burned at complete rest — lying in bed for 24 hours without moving.
Example:
1,650 kcal/day
TDEE
Total Daily Energy Expenditure — BMR multiplied by your activity level (1.2× to 1.9×).
Example (Moderate Activity):
2,310 kcal/day
TDEE is the number you use to set calorie targets for weight loss, maintenance, or muscle gain.
The Mifflin-St Jeor BMR Formula
This calculator uses the Mifflin-St Jeor equation, developed in 1990 and recommended by the Academy of Nutrition and Dietetics as the most accurate BMR formula for healthy adults.
For Men
For Women
Why Mifflin-St Jeor?Clinical studies show it's accurate within ±10% for 82% of healthy adults. The older Harris-Benedict equation (1919) tends to overestimate by 5–15%.
TDEE Activity Level Multipliers
| Activity Level | Multiplier | Description |
|---|---|---|
| Sedentary | BMR × 1.2 | Little to no exercise, desk job |
| Lightly Active | BMR × 1.375 | Light exercise 1–3 days/week |
| Moderately Active | BMR × 1.55 | Moderate exercise 3–5 days/week |
| Very Active | BMR × 1.725 | Hard exercise 6–7 days/week |
| Extra Active | BMR × 1.9 | Very hard exercise, physical job, or training twice/day |
Most people overestimate their activity level. If unsure, choose the lower category.
How to Use Your TDEE for Weight Goals
Weight Loss
Target:
TDEE − 500 kcal/day
A 500 kcal daily deficit creates a 3,500 kcal weekly deficit, resulting in approximately 0.5 kg (1 lb) fat loss per week.
Maintenance
Target:
Eat at TDEE
Calories in equals calories out. Weight stays stable. Body composition can still improve with training.
Muscle Gain
Target:
TDEE + 250–500 kcal/day
A modest surplus supports muscle protein synthesis. Pair with 1.6–2.2 g protein per kg body weight.
BMR vs RMR vs BMI — Common Confusion Clarified
BMR (Basal Metabolic Rate)
Calories burned at complete rest. Measured in a dark room after 8 hours of sleep and 12 hours of fasting.
RMR (Resting Metabolic Rate)
Similar to BMR but slightly higher (5–10%) because it includes minimal arousal — sitting upright, light digestion. Easier to measure clinically.
BMI (Body Mass Index)
Completely different metric. BMI = weight (kg) / height² (m²). Used to categorize underweight, normal, overweight, or obese. Does NOT measure calories.