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BMR Calculator
Think of BMR as your body's "rent". It's the calories you pay just to exist. Breathing, blinking, keeping your heart beating. If you eat less than this, your body freaks out. Let's find your number.
Your Information
Your BMR
Daily Calories by Activity
What is BMR? (The "Coma" Calories)
Your Basal Metabolic Rate (BMR) is the number of calories you would burn if you stayed in bed all day, didn't move, didn't think too hard, and just existed. It's the energy cost of keeping your lights on.
💡 Expert Tip from Sarah Jenkins, RD
Never eat below your BMR. I see this all the time. People crash diet at 1,200 calories when their BMR is 1,500. Your body thinks it's starving, slows down your metabolism, and holds onto fat. It's counterproductive. Eat at least your BMR, and create a deficit through movement.
BMR vs. TDEE: Don't Mix Them Up
BMR (Basal Metabolic Rate): Calories burned at rest. (e.g., 1,600)
TDEE (Total Daily Energy Expenditure): Calories burned in real life (walking, working, exercising). (e.g., 2,200)
If you want to lose weight, you usually aim for a number between your BMR and TDEE.
⚠️ Common Mistake: "I have a slow metabolism"
Most people don't have a "slow metabolism." They have a "low activity level" or "underestimated calorie intake." Unless you have a diagnosed thyroid issue, your BMR is likely very predictable based on your height, weight, and age. The math doesn't lie.
Which Formula is Best?
Mifflin-St Jeor: The gold standard. Developed in 1990. It's what most doctors and dietitians use today. We use this by default.
Harris-Benedict: The old school one (1919). It tends to overestimate calories a bit, which isn't great for weight loss.
Reviewed by Sarah Jenkins, RD
Registered Dietitian
Sarah helps clients fuel their bodies properly instead of starving them.
Frequently Asked Questions
What is BMR and why does it matter?
BMR (Basal Metabolic Rate) is the calories you burn just existing—breathing, keeping your heart beating, etc. It's your body's "rent". Never eat below your BMR or your metabolism slows down. It's the foundation for calculating weight loss/gain calories.
What's the difference between BMR and TDEE?
BMR = calories burned at rest (lying in bed all day). TDEE = BMR × activity multiplier (real life with walking, working, exercising). For weight loss, eat between your BMR and TDEE. Example: BMR 1,600, TDEE 2,200, eat 1,800 for safe fat loss.
Which BMR formula is most accurate?
Mifflin-St Jeor is the gold standard (developed 1990). Harris-Benedict is old school (1919) and overestimates calories. Most dietitians and doctors use Mifflin-St Jeor. We default to it for a reason.