About

Your Basal Metabolic Rate (BMR) represents the number of calories your body burns while at complete rest to maintain vital functions like breathing, circulation, and cell production. It is the absolute floor of your daily energy needs. Consuming fewer calories than your BMR for extended periods is generally counterproductive and can slow down metabolism.

To obtain a practical caloric target, BMR must be multiplied by an activity factor to find the Total Daily Energy Expenditure (TDEE). This tool uses the Mifflin-St Jeor equation, widely considered the most accurate formula for modern populations, to provide the baseline data needed for weight loss or muscle gain protocols.

Formulas

The Mifflin-St Jeor Equation:

For Men:

P = 10w + 6.25h − 5a + 5

For Women:

P = 10w + 6.25h − 5a − 161

Where w is weight in kg, h is height in cm, and a is age in years.

Reference Data

Activity Level	Multiplier	Description
Sedentary	1.2	Desk job, little to no exercise.
Lightly Active	1.375	Light exercise 1-3 days/week.
Moderately Active	1.55	Moderate exercise 3-5 days/week.
Very Active	1.725	Hard exercise 6-7 days/week.
Extra Active	1.9	Physical job or 2x training per day.

Frequently Asked Questions

BMR (Basal Metabolic Rate) is measured under strict laboratory conditions (fasted, just woke up). RMR (Resting Metabolic Rate) is less strict. In practice, they are often used interchangeably, though RMR is usually slightly higher.

Yes. Muscle tissue burns more calories at rest than fat tissue. The Mifflin-St Jeor equation assumes average body composition. If you are very muscular, this calculator may slightly underestimate your BMR.

A common standard is a deficit of 500 calories below your TDEE to lose roughly 1 lb (0.45 kg) per week. Drastic deficits are not recommended as they can lead to muscle loss and metabolic adaptation.