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BMR Harris-Benedict Equation

Calculate your basal metabolic rate using the Harris-Benedict equation

 

BMR Harris-Benedict Equation

Understanding your basal metabolic rate (BMR) is fundamental to managing body weight, energy balance, and metabolic health. The BMR Harris-Benedict Equation is one of the most widely used formulas for estimating how many calories your body burns at rest.

This calculator applies the Harris-Benedict equation to estimate your daily resting energy expenditure based on age, sex, weight, and height. It provides a science-based starting point for determining calorie intake, planning a deficit or surplus, and supporting long-term metabolic optimization.

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 BMR Harris-Benedict Equation

Basal metabolic rate represents the number of calories your body requires to maintain essential physiological functions at rest, including breathing, circulation, and cellular metabolism. The BMR Harris-Benedict Equation was first developed in 1919 and later revised to improve accuracy across populations.

The revised Harris-Benedict formulas are:

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 calculated, it can be multiplied by an activity factor to estimate total daily energy expenditure (TDEE). While predictive equations are estimates rather than direct measurements, the BMR Harris-Benedict Equation remains a widely accepted and practical tool for nutritional planning and weight management.

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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.

    BMR represents calories burned at complete rest. TDEE includes BMR plus calories burned through daily activities and exercise. TDEE is typically higher than BMR.

    The equation provides a reasonable estimate for most individuals. However, factors such as muscle mass, hormonal status, and metabolic adaptation can influence actual energy expenditure.

    Yes. Lean body mass is metabolically active. Increasing muscle mass can modestly raise basal metabolic rate and support long-term metabolic health.

    No. BMR represents resting needs only. Calorie planning should consider total daily energy expenditure, goals, and health context.

    The BMR Harris-Benedict Equation offers a structured and evidence-based method for estimating basal metabolic rate. It serves as a foundational tool for calorie planning, weight management, and metabolic optimization.

    By understanding your BMR and adjusting intake based on activity level and goals, you can create more precise nutrition strategies. Using the BMR Harris-Benedict Equation supports a data-driven approach to long-term health and energy balance.