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Harris Benedict Equation

Calculate your Basal Metabolic Rate accurately to optimize nutrition and energy balance.

Harris Benedict Equation

The Harris Benedict Equation is a scientifically validated formula used to estimate Basal Metabolic Rate (BMR), the amount of energy your body requires at rest to maintain essential physiological functions. Understanding BMR is key for managing weight, planning nutrition, and optimizing overall health.

By incorporating factors such as age, sex, weight, and height, the Harris Benedict Equation provides a personalized estimate of daily caloric needs. This allows individuals to make evidence-based decisions about diet, exercise, and lifestyle.

Harris–Benedict BMR Calculator

Calculate your Basal Metabolic Rate and Total Daily Energy Expenditure using the original (1919) or revised (Roza & Shizgal, 1984) Harris–Benedict equation.

Your Profile (Step 1 of 3)
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Your Profile

Enter your biological sex, age, height and weight. These four variables are the inputs to both versions of the Harris–Benedict equation.

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Male
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Female
Valid range: 18–120 years.
Please enter an age between 18 and 120.
Please enter a height between 100 and 250 cm.
Please enter a weight between 20 and 500 kg.
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Estimated BMR (kcal / day)
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Equation & Activity Level

Choose which version of the Harris–Benedict equation to use, then select your daily activity level to calculate your Total Daily Energy Expenditure (TDEE).

Original (1919)
Harris & Benedict — PNAS 1919. Published by the Carnegie Institution of Washington. Based on 239 subjects.
Historic
Revised (1984)
Roza & Shizgal — Am J Clin Nutr 1984. Recalculated on 337 subjects. Stronger R² (0.77 / 0.68).
More Accurate
Activity multipliers per Harris & Benedict (1919) as popularised by McArdle, Katch & Katch, Exercise Physiology (2010).

Basal Metabolic Rate (BMR)

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kcal / day
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Sex
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Age
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Height
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Weight

Total Daily Energy Expenditure (TDEE)

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kcal / day
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BMR

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kcal / day

TDEE

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kcal / day

Activity factor

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PAL multiplier

Equation

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version

Step-by-step calculation

Equation used: --
Formula: --
BMR calculation: --
TDEE: BMR × activity factor
TDEE result: --

Your TDEE at every activity level

Activity level Multiplier TDEE (kcal/day) Notes

Using your TDEE for weight goals

Goal Daily calorie target Expected rate
~7,700 kcal = 1 kg body weight change (Hall KD, Obesity Reviews, 2008). Never eat below your BMR without medical supervision.

Harris–Benedict equation versions compared

Version Men Women Sample size & accuracy
Original (Harris & Benedict, 1919) 66.47 + (13.75 × kg) + (5.003 × cm) − (6.755 × age) 655.1 + (9.563 × kg) + (1.850 × cm) − (4.676 × age) n=239 (R²=0.64/0.36). Tends to overestimate by ~5%.
Revised (Roza & Shizgal, 1984) 88.362 + (13.397 × kg) + (4.799 × cm) − (5.677 × age) 447.593 + (9.247 × kg) + (3.098 × cm) − (4.330 × age) n=337 (R²=0.77/0.68). Improved accuracy over original.
Mifflin–St Jeor (1990) 10 × kg + 6.25 × cm − 5 × age + 5 10 × kg + 6.25 × cm − 5 × age − 161 n=498. Most accurate: 82% within ±10% of measured (Frankenfield et al., J Am Diet Assoc, 2005).
Medical disclaimer The Harris–Benedict equation was derived from measurements of early 20th-century Americans and may overestimate BMR by approximately 5% compared to modern populations (Harris & Benedict, PNAS, 1919; Roza & Shizgal, Am J Clin Nutr, 1984). For greater accuracy in modern populations, the Mifflin–St Jeor equation (1990) is generally recommended by the Academy of Nutrition and Dietetics (Frankenfield et al., J Am Diet Assoc, 2005). BMR calculators do not account for body composition, hormonal status, medications, or individual metabolic variation. Do not restrict calories below your BMR without medical supervision. Consult a registered dietitian or physician before making significant dietary changes.

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Understanding Harris Benedict Equation

The Harris Benedict Equation calculates BMR using the following formulas:

  • For men: BMR = 88.362 + (13.397 × weight in kg) + (4.799 × height in cm) − (5.677 × age in years)

  • For women: BMR = 447.593 + (9.247 × weight in kg) + (3.098 × height in cm) − (4.330 × age in years)

Once BMR is determined, it can be multiplied by an activity factor to estimate total daily energy expenditure (TDEE), which reflects the calories needed to maintain weight based on activity level.

The Harris Benedict Equation is widely used in clinical nutrition, fitness, and preventive health. It provides a reliable framework for setting caloric goals, whether the objective is weight maintenance, weight loss, or weight gain.

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    FAQ

    Understanding this calculator can raise questions. Here you’ll find clear, evidence-based answers to help you interpret your results and understand the science behind it.

    The equation provides a reliable estimate of BMR, though individual metabolic differences may cause slight variations. It is most useful for planning dietary and activity adjustments.

    Accurate weight, height, age, and sex are needed to calculate BMR using the Harris Benedict Equation.

    Yes, by combining BMR with activity factors, it helps estimate daily caloric needs for weight loss, maintenance, or gain.

    While broadly applicable, it may be less precise for highly muscular individuals, older adults, or people with metabolic conditions. Adjustments may be necessary.

    The Harris Benedict Equation is a foundational tool for estimating Basal Metabolic Rate and guiding caloric planning. It provides evidence-based insights for nutrition, weight management, and overall health optimization.

    By using this equation to understand energy needs, individuals can make informed dietary and lifestyle choices that support long-term wellness, metabolic balance, and healthy body composition.