Harris-Benedict Equation Calculator

The Harris-Benedict equation is a formula used to estimate Basal Metabolic Rate (BMR), which represents the number of calories the body needs at rest to maintain basic physiological functions such as breathing and circulation.

Developed by James Arthur Harris and Francis Gano Benedict in the early 20th century, the equation takes into account factors such as age, gender, weight, and height to estimate BMR.

It serves as a fundamental tool in nutrition and weight management, providing a baseline estimate of calorie needs for individuals.

The formula for BMR using the Harris-Benedict equation for males is:

BMR (kcal/day) = 66.5 + (13.75 × weight in kg) + (5.003 × height in cm) - (6.75 × age in years)

On the other hand, the formula for Harris-Benedict BMR for females is:

BMR (kcal/day) = 655.1 + (9.563 × weight in kg) + (1.850 × height in cm) - (4.676 × age in years)

You can simply enter height, weight, age and gender in your preferred units in the calculator above to get your result.

Basal Metabolic Rate (BMR) reflects the calories the body requires at rest to sustain vital functions like breathing and circulation. It's calculated using equations like the Harris-Benedict formula, which consider factors such as age, gender, weight, and height.

Total Daily Energy Expenditure (TDEE), meanwhile, encompasses all calories expended in a day, including BMR, physical activity, and the energy used during digestion (the thermic effect of food). TDEE offers a broader estimate of daily calorie needs, accounting for both resting metabolic rate and activity level.

The main difference between BMR and TDEE lies in their scope: BMR focuses solely on the body's energy needs at rest, while TDEE considers additional energy expended through physical activity and digestion. Consequently, TDEE typically exceeds BMR, as it includes all daily activities and metabolic processes.

Understanding both BMR and TDEE is crucial for effective weight management, guiding individuals in adjusting their calorie intake to align with their energy requirements and goals.

The Harris-Benedict formula is widely used to estimate BMR, but it is important to be aware of some of its limitations:

• Population Bias: Developed from data of specific demographics, the equation may not accurately estimate metabolic rates for diverse populations.
• Age and Activity Simplifications: Fixed age and activity factors oversimplify individual variations, potentially leading to inaccurate estimations.
• Gender-based Assumptions: Separate equations for males and females may not fully account for gender-specific metabolic differences.
• Inadequate for Extreme Cases: The equation may not provide accurate estimates for individuals with extreme body weights or metabolic conditions.
• Lack of Consideration for Muscle Mass: It doesn't directly consider variations in muscle mass, potentially underestimating metabolic rates in individuals with higher muscle mass. The Katch-McArdle formula accounts for this on the other hand.

You can estimate BMR with a couple of other formulas:

• Katch-McArdle equation
• Mifflin-St Jeor equation
• Schofield equation
• BMR calculator - comparing all formulas

The alternatives rely on different formulas and may produce slightly different estimates.

You can read about BMR in this Wikipedia article.