BMR Calculator
Calculate your Basal Metabolic Rate
Formula
Men: 10×W + 6.25×H - 5×A + 5
Women: 10×W + 6.25×H - 5×A - 161
(Mifflin-St Jeor Equation)
BMR Factors
| Age | ↓2%/decade after 20 |
| Muscle | More = Higher BMR |
| Sex | Men typically higher |
| Hormones | Thyroid affects BMR |
Related Calculators
Complete Guide to BMR Calculator
Basal Metabolic Rate (BMR) is the number of calories your body needs to perform essential life-sustaining functions while at complete rest. Think of it as the energy cost of simply existing – breathing, circulating blood, regulating temperature, and maintaining organ function.
Understanding Your BMR
BMR accounts for approximately 60-75% of your total daily calorie expenditure. Even if you stayed in bed all day, your body would still burn these calories. The Mifflin-St Jeor equation, used in this calculator, is considered the most accurate formula for estimating BMR and is recommended by the Academy of Nutrition and Dietetics.
Factors That Affect BMR
- Age: BMR decreases about 2% per decade after age 20, primarily due to muscle loss.
- Body Composition: Muscle tissue burns more calories than fat tissue, even at rest. This is why strength training can boost metabolism.
- Sex: Men typically have 10-15% higher BMR than women of similar size due to greater muscle mass and lower body fat.
- Genetics: Some people naturally have faster or slower metabolisms.
- Hormones: Thyroid hormones significantly impact metabolic rate. Conditions like hypothyroidism can lower BMR.
How to Use Your BMR
Your BMR is the foundation for calculating your Total Daily Energy Expenditure (TDEE). Multiply your BMR by an activity factor (1.2-1.9) based on your lifestyle to get TDEE. Never eat below your BMR for extended periods, as this can slow metabolism and cause muscle loss.
Boosting Your BMR Naturally
While you can't dramatically change your BMR, certain habits help: build muscle through strength training, get adequate sleep, eat enough protein, stay hydrated, and avoid crash diets that can lower metabolism.
Frequently Asked Questions
BMR (Basal Metabolic Rate) is measured under strict conditions: complete rest, fasting, and controlled temperature. RMR (Resting Metabolic Rate) is measured under less restrictive conditions and is typically 10-20% higher. For practical purposes, they're often used interchangeably.
BMR tells you the minimum calories your body needs. For sustainable weight loss, you should eat above your BMR but below your TDEE. Eating below BMR can trigger metabolic adaptation, making future weight loss harder.
The Mifflin-St Jeor equation is accurate within 10% for most people. Individual variations due to genetics, hormones, and body composition mean your actual BMR may differ. Track your weight and adjust calories based on real-world results.
Yes, primarily through building muscle mass. Each pound of muscle burns about 6 calories per day at rest, compared to 2 calories for fat. High-intensity exercise can also temporarily boost metabolism for hours after your workout (EPOC effect).
The 'breakfast boosts metabolism' claim is largely a myth. Total daily calorie intake matters more than meal timing for most people. Eat when it works for your schedule and lifestyle.
Age-related BMR decline is primarily due to loss of muscle mass (sarcopenia) and hormonal changes. Regular strength training can slow this decline significantly, preserving muscle mass and metabolic rate.
You should eat at least your BMR calories to support basic body functions. For weight loss, eat between BMR and TDEE. For weight maintenance, eat at TDEE. Never go below BMR for extended periods.