BMR Calculator

What Is Basal Metabolic Rate (BMR)?

Your Basal Metabolic Rate (BMR) is the number of calories your body burns every day at complete rest — just to keep you alive. It powers breathing, blood circulation, brain function, cell repair, and temperature regulation. BMR typically accounts for 60-70% of your total daily calorie expenditure.

Knowing your BMR is the first step to understanding your calorie needs. Once you know your BMR, you can multiply it by an activity factor to get your Total Daily Energy Expenditure (TDEE), which is what you actually use to set calorie targets for fat loss, maintenance, or muscle gain.

The Formulas Behind This Calculator

• Mifflin-St Jeor (recommended) — The most accurate equation for the general population according to the American Dietetic Association. Uses weight, height, age, and sex.
• Harris-Benedict — One of the oldest BMR equations (1919, revised 1984). Tends to overestimate by 5-15% compared to modern measurements but is still widely referenced.

Factors That Affect Your BMR

• Muscle mass — More muscle means a higher BMR. Strength training is the most effective way to increase your resting metabolism.
• Age — BMR decreases roughly 1-2% per decade after age 20, mainly due to muscle loss.
• Sex — Males typically have a higher BMR due to greater lean mass and higher testosterone.
• Body size — Larger bodies burn more calories at rest simply because there is more tissue to maintain.
• Dieting history — Prolonged calorie restriction can reduce BMR through metabolic adaptation.

How to Use Your BMR

Your BMR alone is not enough to set calorie targets — you need your TDEE. Multiply your BMR by an activity factor:

• Sedentary — BMR × 1.2
• Light activity — BMR × 1.375
• Moderate activity — BMR × 1.55
• Active — BMR × 1.725
• Very active — BMR × 1.9

Or use our Calorie Calculator which does this automatically and shows cutting, maintenance, and bulking targets.

Frequently Asked Questions

What is BMR?

BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest to maintain basic life functions like breathing, circulation, and cell repair. It typically accounts for 60-70% of your total daily calorie burn.

What is the difference between BMR and TDEE?

BMR is calories burned at rest. TDEE adds all daily activity on top — walking, exercise, digestion, and non-exercise movement. TDEE is the number you use for nutrition planning; BMR is the baseline.

Which BMR formula is most accurate?

The Mifflin-St Jeor equation is considered the most accurate for the general population. The Harris-Benedict equation tends to overestimate slightly. If you know your lean body mass, the Katch-McArdle formula is the most precise.

Can I increase my BMR?

Yes. Building muscle mass is the most effective way to increase BMR since muscle tissue burns more calories at rest than fat tissue. Strength training, adequate protein intake, and avoiding prolonged severe calorie deficits all help.

Should I eat at my BMR to lose weight?

No. Eating at your BMR means you are already in a significant deficit since it does not account for any activity. Most people should eat at their TDEE minus 300-500 calories for sustainable fat loss. Eating below BMR risks muscle loss and metabolic slowdown.

Related Free Tools

• Calorie Calculator — Calculate your TDEE and see cutting, maintenance, and bulking calorie targets.
• Macro Calculator — Get your daily protein, fat, and carb targets based on your calorie goal.
• Body Fat Calculator — Estimate your body fat percentage using the Navy method.