1,672
kcal/day
2,591
kcal/day
2,073
kcal/day
2,850
kcal/day
112
g/day
56
g/day
72
g/day
1,672
kcal/day
2,591
kcal/day
2,073
kcal/day
2,850
kcal/day
112
g/day
56
g/day
72
g/day
The Harris-Benedict equation is one of the oldest and most historically significant formulas in nutrition science. Originally published in 1918 by James Arthur Harris and Francis Gano Benedict at the Carnegie Institution of Washington, this equation was the first widely-adopted method for estimating Basal Metabolic Rate from simple anthropometric measurements. Their groundbreaking study measured the metabolic rates of 239 individuals using indirect calorimetry and derived regression equations relating BMR to height, weight, age, and gender.
The version used in this calculator is the 1984 revision by Roza and Shizgal, which updated the original coefficients using a larger and more diverse dataset. The revised Harris-Benedict equation addresses some of the overestimation bias present in the original formula, particularly for obese individuals. However, even the revised version tends to overestimate BMR by about 5% compared to direct measurements, which is why the Mifflin-St Jeor equation is now recommended as more accurate by many nutrition organizations.
Despite being partially superseded by newer equations, the Harris-Benedict formula remains extensively used in clinical practice, hospital nutrition departments, and dietary counseling worldwide. Its enduring popularity stems from its long track record, extensive validation across diverse populations, and deep integration into clinical protocols and medical software. Many healthcare institutions continue to use Harris-Benedict as their standard because it has been validated in their specific patient populations over decades.
The Harris-Benedict equation differs from the Mifflin-St Jeor in its mathematical structure. While Mifflin uses a simpler linear form (10W + 6.25H - 5A ± constant), Harris-Benedict uses larger constant terms and different coefficients for each variable, reflecting its derivation from an older and differently constructed dataset. For males, the base constant is 88.362, compared to Mifflin's effective constant of 5. For females, the structures diverge even more, with Harris-Benedict using a large constant of 447.593.
This calculator computes your Harris-Benedict BMR, multiplies it by your activity factor to estimate TDEE, and provides basic macronutrient targets as starting points. The protein target of 1.6 g/kg reflects the minimum recommended for physically active individuals, and the fat target of 25% of TDEE ensures adequate essential fatty acid intake and hormone production. These macro suggestions are general starting points — adjust based on your specific goals, dietary preferences, and response to the diet.
The revised Harris-Benedict equation (1984): Males: BMR = 88.362 + 13.397 x W + 4.799 x H - 5.677 x A. Females: BMR = 447.593 + 9.247 x W + 3.098 x H - 4.330 x A. W=weight(kg), H=height(cm), A=age(years). TDEE = BMR x Activity Factor. Protein target = 1.6 g per kg body weight (minimum for active individuals). Fat target = 25% of TDEE divided by 9 kcal/g.
Harris-Benedict BMR tends to be slightly higher than Mifflin-St Jeor, so your TDEE estimate may be 5-10% above what Mifflin would give. If using this for weight loss, consider eating 10% below the calculated TDEE to account for this potential overestimation. The macro targets are starting points: adjust protein up for strength athletes (2.0-2.2 g/kg) and adjust fat based on dietary preference (20-35% of calories).
Inputs
Results
Harris-Benedict BMR of 1,864 kcal gives TDEE of 2,889. Compare with Mifflin TDEE of ~2,790 for the same person.
Inputs
Results
Harris-Benedict gives BMR 1,393 and TDEE 2,159 kcal/day with protein target of 96g and fat target of 60g.
The revised (1984) Harris-Benedict equation overestimates BMR by about 5% on average compared to measured values. It is less accurate than the Mifflin-St Jeor equation but still provides useful estimates, especially for normal-weight individuals.
Harris-Benedict has over a century of clinical use and validation data. Many hospitals, nutrition software programs, and clinical protocols still use it. If your healthcare provider uses Harris-Benedict, consistency with their calculations may be more important than marginal accuracy improvement.
The 1918 original used different coefficients and tended to overestimate BMR more. The 1984 Roza-Shizgal revision updated the coefficients using a larger dataset, reducing the overestimation bias, particularly for obese individuals.
Men and women have different body compositions at the same height, weight, and age. Men typically have more muscle mass and less fat, which increases BMR. The different constants and coefficients in the gender-specific equations capture these physiological differences.
Be honest and conservative. Sedentary (1.2): desk job, no exercise. Lightly Active (1.375): 1-3 light sessions/week. Moderate (1.55): 3-5 sessions/week. Very Active (1.725): daily hard training. Extra Active (1.9): professional athlete. Most people should choose Sedentary or Lightly Active.
Yes, but consider that Harris-Benedict may overestimate your needs by 5-10%. Start at the calculated TDEE minus 500 kcal for weight loss, and if you are not losing 0.5-1 kg per week after 2-3 weeks, reduce by another 100-200 kcal.
A common starting point is 30% protein, 25% fat, 45% carbohydrates. For weight loss, higher protein (35%) improves satiety and muscle preservation. For endurance athletes, higher carbohydrates (55-60%) support training. Adjust based on your goals and how your body responds.
Research shows 1.6 g/kg is the minimum needed to optimize muscle protein synthesis in active individuals. The International Society of Sports Nutrition recommends 1.4-2.0 g/kg for exercising people. For strength athletes or during caloric deficit, 2.0-2.4 g/kg may be beneficial.
Harris-Benedict tends to overestimate BMR in obese individuals because it uses total body weight, including metabolically less-active fat tissue. The Katch-McArdle equation, which uses lean body mass, may be more accurate for obese individuals.
James Arthur Harris was a botanist and biometrician, and Francis Gano Benedict was a chemist and physiologist at the Carnegie Nutrition Laboratory. Their 1918 publication, 'A Biometric Study of Basal Metabolism in Man,' analyzed 239 subjects and established the framework for metabolic rate prediction that is still used today.
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