About

Effective nutritional planning begins with establishing a baseline for energy expenditure. This calculator utilizes the Mifflin-St Jeor equation, widely considered the most accurate formula for estimating Basal Metabolic Rate (BMR) in clinical settings. The BMR represents the energy required to maintain vital physiological functions - breathing, circulation, and cell production - while at complete rest. To determine the Total Daily Energy Expenditure (TDEE), this baseline is adjusted by an Activity Factor. Accurate caloric estimation is crucial for athletes managing performance, patients recovering from surgery, or individuals managing metabolic conditions. Underestimating caloric needs can lead to catabolic states, while overestimation results in unwanted adipose tissue accumulation.

Formulas

The Mifflin-St Jeor equation calculates BMR based on metric units. The formula differs slightly between biological sexes.

{

P = 10m + 6.25h − 5a + 5 (Male)P = 10m + 6.25h − 5a − 161 (Female)

Where m is mass (kg), h is height (cm), and a is age (years). The final TDEE is calculated as:

TDEE = P × k

Reference Data

Activity Level	Multiplier (k)	Description
Sedentary	1.2	Little or no exercise, desk job
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

Frequently Asked Questions

The standard Mifflin-St Jeor equation relies on total body weight. Individuals with very high lean muscle mass may find this formula underestimates their needs, as muscle tissue is more metabolically active than fat tissue. The Katch-McArdle formula is preferred if body fat percentage is known.

Energy needs change as weight fluctuates. It is recommended to recalculate your TDEE for every 5-10 lbs (2-5 kg) of weight change to ensure your intake remains aligned with your goals.

Protein has a higher Thermic Effect of Food (TEF) compared to fats and carbohydrates, meaning the body burns more calories digesting it. Furthermore, adequate protein intake is essential to preserve lean tissue during a caloric deficit.

Yes. Most modern office workers who do not intentionally exercise fit the "Sedentary" category. Even standing desks or short walks typically do not elevate the heart rate enough to move into the "Lightly Active" tier.