Harris-Benedict formulas
Weight W in kg, height H in cm, age A in years.
| Version | Men | Women |
|---|---|---|
| Revised (1984) | 88.362 + 13.397W + 4.799H − 5.677A | 447.593 + 9.247W + 3.098H − 4.330A |
| Original (1918) | 66.473 + 13.7516W + 5.0033H − 6.755A | 655.0955 + 9.5634W + 1.8496H − 4.6756A |
How the versions compare
For two 50-year-olds, the results in calories per day:
| Person | HB revised | HB original | Mifflin |
|---|---|---|---|
| Man, 5′11″, 200 lb | 1,885 | 1,879 | 1,789 |
| Woman, 5′4″, 160 lb | 1,406 | 1,416 | 1,331 |
Harris-Benedict usually lands somewhat above Mifflin-St Jeor. That gap is one reason many professionals switched defaults: studies comparing predictions with measured resting rates found Harris-Benedict tended to overestimate for many people.
When Harris-Benedict is a reasonable choice
It can be handy if you are following a plan or textbook that was built around it, or if you want a second estimate to see the likely range. If the two equations differ by 100 calories for you, your real number could easily be on either side. Your weight trend over a few weeks will tell you which estimate fits better; see how to find your maintenance calories.
Frequently asked questions
What is the Harris-Benedict equation?
It is one of the oldest formulas for basal metabolic rate, published by James Arthur Harris and Francis Gano Benedict in 1918–1919 from measurements of 239 adults. Roza and Shizgal re-derived the coefficients in 1984; that “revised” version is what this calculator uses.
Is the Harris-Benedict equation still used?
Yes, though many dietitians now default to Mifflin-St Jeor, which reviews have found to be more often within 10% of measured resting rate. Harris-Benedict tends to give slightly higher numbers, so it is useful as a comparison.
What is the difference between the original and revised Harris-Benedict?
Same structure, different coefficients, re-derived by Roza and Shizgal in 1984. In practice the two versions usually land within a few dozen calories of each other.
What activity factors go with Harris-Benedict?
The same factors used with any BMR equation: about 1.2 for sedentary, 1.375 lightly active, 1.55 moderately active, 1.725 very active and 1.9 extra active. They are conventions, not part of the original 1918 paper.