BMR Calculator
Use this BMR calculator to find your exact Basal Metabolic Rate in seconds. Whether you need a BMR calculator for weight loss or muscle building, knowing your resting energy burn helps you set sustainable nutrition targets.
What is Basal Metabolic Rate (BMR)?
Basal Metabolic Rate (BMR) is the total number of calories your body burns every 24 hours to carry out vital survival functions. Even if you stay in bed all day, your brain, heart, lungs, kidneys, and liver demand energy to keep you alive.
BMR accounts for 60% to 75% of your daily energy burn. It excludes active movement, exercise, and the energy needed to digest food.
The Mifflin-St Jeor Equation
Published in 1990, the Mifflin-St Jeor equation remains the gold standard in nutrition science, consistently outperforming the legacy Harris-Benedict formula for non-obese and obese adults alike.
BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) + 5BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) - 161BMR = 370 + (21.6 × Lean Body Mass in kg)Use Katch-McArdle if you know your exact body fat percentage, as lean body mass drives metabolic expenditure more than total scale weight.
How to Calculate BMR by Hand
Follow these four steps to run the math manually for a 35-year-old male weighing 180 lbs (81.65 kg) at 5 ft 10 in (177.8 cm):
- Step 1 (Weight): 10 × 81.65 = 816.5
- Step 2 (Height): 6.25 × 177.8 = 1,111.25
- Step 3 (Age): 5 × 35 = 175
- Step 4 (Final Total): 816.5 + 1,111.25 - 175 + 5 = 1,757.75 calories/day
This individual burns roughly 1,758 calories each day just maintaining basic organ function.
BMR vs TDEE: What Is the Difference?
A standard BMR vs TDEE calculator comparison comes down to physical movement:
| Metric | What It Measures | How to Use It |
|---|---|---|
| BMR | Calories burned at absolute rest (coma level) | Your absolute minimum daily calorie intake floor |
| TDEE | BMR × Activity Multiplier (work, steps, workouts) | Your maintenance calories for weight loss or gain |
Common activity level factor multipliers include: Sedentary (1.2), Light (1.375), Moderate (1.55), and Very Active (1.725).
Frequently Asked Questions
What is a good BMR for my age?
A standard BMR for adult men averages between 1,600 and 1,800 calories daily, while adult women typically average between 1,300 and 1,500 calories. Your rate naturally drops by roughly 1% to 2% per decade after age 20 as lean body mass decreases.
How many calories should I eat based on my BMR?
Never eat below your BMR without direct medical supervision. To lose fat, multiply your BMR by your activity multiplier to get your TDEE, then subtract 300 to 500 calories from that higher TDEE number.
Is BMR the same as calories burned at rest?
Not quite, though they are close. BMR measures the absolute minimum energy needed to stay alive in an inactive, post-absorptive state. Resting Metabolic Rate (RMR) is slightly less strict and includes minor energy burned from low-effort resting movements.
How accurate is the Mifflin-St Jeor equation?
Clinical studies show the Mifflin-St Jeor equation predicts resting metabolic rates within 10% of measured values for roughly 80% of healthy adults, making it more reliable than the older Harris-Benedict formula.
BMR Calculator
* Basal metabolic rate and energy expenditure estimations are calculated using standard scientific equations (Mifflin-St Jeor). Individual metabolic rates vary with lean muscle mass, genetics, and hormonal factors.
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