BMR Calculator — Basal Metabolic Rate

Age

yrs

Weight

Height

Your BMR

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calories / day at rest

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Sedentary TDEE

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Active TDEE

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Very Active TDEE

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Weight Loss Target

About the BMR Calculator

Your Basal Metabolic Rate is the minimum number of calories your body needs to function at complete rest — covering breathing, circulation, temperature regulation, and cell repair. It accounts for roughly 60–75% of your total daily calorie burn.

Mifflin-St Jeor Equation

This calculator uses the Mifflin-St Jeor equation, published in 1990 and widely regarded as the most accurate BMR formula for the general population. For men: BMR = (10 × kg) + (6.25 × cm) − (5 × age) + 5. For women: same formula but −161 instead of +5.

From BMR to TDEE

Multiply your BMR by an activity factor to get your Total Daily Energy Expenditure (TDEE). Sedentary (little exercise) = BMR × 1.2. Lightly active = BMR × 1.375. Moderately active = BMR × 1.55. Very active = BMR × 1.725. Extremely active = BMR × 1.9.

BMR vs TDEE and how to use them

BMR (Basal Metabolic Rate) is the minimum energy your body needs at complete rest. TDEE (Total Daily Energy Expenditure) is your actual daily calorie need accounting for activity. To estimate TDEE, multiply BMR by an activity multiplier: sedentary (1.2), lightly active (1.375), moderately active (1.55), very active (1.725), extremely active (1.9).

Weight loss — a deficit of 500 kcal/day below TDEE typically produces ~0.5 kg loss per week
Muscle gain — a surplus of 200-500 kcal above TDEE supports muscle growth with minimal fat gain
Maintenance — eating at TDEE maintains current weight; adjust based on 2-4 week weight trend
Dieting adaptation — prolonged deficits reduce BMR; diet breaks and refeed days help mitigate this

Frequently Asked Questions

What is BMR?

BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest to maintain basic functions like breathing, circulation, and cell production.

Which BMR formula does this calculator use?

We use the Mifflin-St Jeor equation, which is considered the most accurate for the general population. It accounts for weight, height, age, and sex.

What is the difference between BMR and TDEE?

BMR is calories burned at rest. TDEE (Total Daily Energy Expenditure) is BMR multiplied by an activity factor — the total calories you need per day including exercise.

How do I use my BMR to lose weight?

To lose weight, eat fewer calories than your TDEE. A deficit of 500 calories per day typically results in about 0.5 kg (1 lb) of weight loss per week.

What is the Mifflin-St Jeor equation?

Mifflin-St Jeor is the most accurate commonly used BMR formula. Men: BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) + 5. Women: BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) − 161. It was validated in a 1990 study and is more accurate than the older Harris-Benedict formula for most populations.

How does BMR relate to weight loss?

BMR represents calories needed at complete rest. Your TDEE (total daily expenditure) is BMR multiplied by an activity factor. Creating a calorie deficit below TDEE causes weight loss. A 500 kcal/day deficit typically produces approximately 0.5 kg/week loss. Deficits below BMR are not recommended without medical supervision.