Basal Metabolic Rate (BMR) is the number of calories your body needs to maintain basic functions — such as breathing, circulation and organ function — while completely at rest.

What formula is used to calculate BMR?

Asterisks Fit uses the Mifflin-St Jeor formula, which is considered one of the most accurate BMR formulas for general use. It takes into account your weight, height, age and sex.

How is BMR different from TDEE?

BMR is your calorie need at complete rest. TDEE (Total Daily Energy Expenditure) multiplies your BMR by an activity factor to account for physical activity throughout the day.

Can I lose weight if I eat only my BMR calories?

Eating at BMR level creates a significant calorie deficit for most people, which can lead to weight loss. However, very low calorie intakes are not recommended without medical supervision as they can affect muscle mass and nutrient adequacy.

Free BMR Calculator

Your Basal Metabolic Rate (BMR) is the number of calories your body needs at complete rest to keep essential functions running — breathing, circulation and organ function. Use this calculator to find your BMR using the standard published Mifflin-St Jeor formula.

Calculate Your BMR

Enter your details to estimate your resting calorie requirement.

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Mifflin-St Jeor Formula

For males:

BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5

For females:

BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161

Example

A 30-year-old female weighing 65 kg at 165 cm: BMR = (10 × 65) + (6.25 × 165) − (5 × 30) − 161 = 650 + 1031.25 − 150 − 161 = 1,370 kcal/day

How to Use Your BMR

BMR is your starting point for calorie planning. On its own, it represents your calorie requirement at complete rest. Most people need significantly more than their BMR to fuel their daily activity.

The next step is to calculate your TDEE (Total Daily Energy Expenditure), which multiplies your BMR by an activity factor to give you your true daily calorie need.

From your TDEE, you can then set a calorie deficit for weight loss or a surplus for muscle gain.

How the Calculation Works

Asterisks Fit BMR calculations are built upon established metabolic research and clinical nutritional guidelines:

Mifflin-St Jeor Equation (1990): Daily resting metabolism (BMR) is estimated using the formula:Men: BMR = (10 × W) + (6.25 × H) − (5 × A) + 5 | Women: BMR = (10 × W) + (6.25 × H) − (5 × A) − 161This formula has been shown in peer-reviewed studies to be one of the most accurate equations for predicting energy expenditure in healthy adults.
Comparison with Harris-Benedict (1918): While older equations can overestimate BMR in modern populations, the Mifflin-St Jeor equation incorporates updated clinical standards that reduce estimation error by up to 10%.
Academy of Nutrition and Dietetics Standards: Mifflin-St Jeor is the primary recommended predictive equation by the Academy of Nutrition and Dietetics for calculating resting energy requirements in healthy individuals.

Formula based on the published equation. Methodology reviewed by the Asterisks editorial team. Last content review: June 2025.

Last Updated: June 2026

TDEE Calculator

Calculate your total daily calorie needs based on activity level.

Calorie Deficit Calculator

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Macro Calculator

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Need Help Applying Your BMR to Your Diet Plan?

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Frequently Asked Questions

Medical Disclaimer: BMR estimates are for informational purposes only. Individual metabolism varies. Consult a registered dietitian or healthcare professional for personalised nutrition guidance. Full disclaimer →