Free BMR calculator
BMR Calculator — Your Basal Metabolic Rate
Your **BMR** — Basal Metabolic Rate — is the energy your body uses just to stay alive: breathing, pumping blood, keeping your brain and organs running. It's the floor of your calorie needs before you move a muscle.
Enter your details for an instant BMR estimate using the Mifflin-St Jeor equation.
Basal metabolic rate (BMR)
1,699kcal/day
Calories your body burns at complete rest.
Estimates only, based on the Mifflin-St Jeor equation. Your real numbers depend on genetics, training, and how your body adapts — which is exactly what WhispCal measures over time.
What your BMR includes
BMR accounts for 60–70% of the calories most people burn in a day. That surprises people — the vast majority of your energy goes to simply existing, not to exercise.
Because it's so large a share, small changes to BMR (from losing muscle, or from a long aggressive diet) have a bigger effect on your daily needs than an extra gym session ever could.
BMR vs. TDEE
BMR is what you'd burn at complete rest. Multiply it by an activity factor and you get your TDEE — your real daily burn including movement and exercise. You set calorie goals from TDEE, not BMR, but BMR is the foundation it's built on.
Never set your calorie target below your BMR for any length of time. Eating under the energy your organs need is the fast track to muscle loss, fatigue, and a metabolism that fights back.
What changes your BMR
Muscle mass is the biggest lever you control — more muscle means a higher BMR around the clock. Age lowers it gradually, and crash dieting can suppress it temporarily. This is why protein and resistance training matter so much: they protect the engine that burns most of your calories.
Frequently asked questions
What is a normal BMR?
BMR varies widely with size, age, and sex, but most adults fall somewhere between 1,300 and 1,900 calories per day. Larger people and those with more muscle sit higher.
Can I increase my BMR?
Yes, modestly. Building muscle through resistance training is the most reliable way — muscle is metabolically active tissue. Eating enough protein and avoiding prolonged crash diets also protects it.
Should I eat at my BMR to lose weight?
No. Eating at or below your BMR is too aggressive and risks losing muscle. Create your deficit from your TDEE instead, and keep intake above your BMR.
Why is my BMR lower than it used to be?
Age, muscle loss, and long periods of dieting can all lower BMR. The good news is resistance training and adequate protein can reverse much of the muscle-related decline.
Keep exploring
Let WhispCal do the math automatically
These numbers are a starting point. WhispCal measures how your body actually responds — logging food in 3 seconds by voice, photo, or barcode — and auto-adjusts your targets as your metabolism changes. Free on iOS and Android.
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