James Harris and Francis Benedict measured the metabolism of 239 people in Boston in the 1910s. Their equation was the standard for most of the 20th century and is still used in hospitals, although modern adults are often slightly over-estimated by it.
How to use the Harris–Benedict Equation Calculator
- Sex
- Age
- Weight
- Height
- Activity level
Results update as you type, and every field accepts the units shown in its menu.
How it works
Enter sex, age, weight and height and choose your activity level. Both versions of the equation are shown so you can compare them.
Activity multipliers
| Activity level | Multiplier |
|---|---|
| Basal metabolic rate (no activity) | 1 |
| Sedentary: little or no exercise | 1.2 |
| Light: exercise 1–3 times a week | 1.375 |
| Moderate: exercise 4–5 times a week | 1.465 |
| Active: daily exercise or intense 3–4 times a week | 1.55 |
| Very active: intense exercise 6–7 times a week | 1.725 |
| Extra active: very intense daily or physical job | 1.9 |
Inputs explained
| Field | What to enter |
|---|---|
| Sex | Choose one: Male, Female |
| Age | In years |
| Weight | Units: kg, lb, st, g |
| Height | Units: cm, in, m, ft, mm |
| Activity level | Choose one: Basal metabolic rate (no activity), Sedentary: little or no exercise, Light: exercise 1–3 times a week, Moderate: exercise 4–5 times a week … |
Health note: this calculator is for education and screening only and is not a diagnosis or treatment advice. Discuss your results with a qualified clinician.
Formula
Revised (1984): men 88.362 + 13.397W + 4.799H − 5.677A; women 447.593 + 9.247W + 3.098H − 4.330A
Original (1919): men 66.5 + 13.75W + 5.003H − 6.755A; women 655.1 + 9.563W + 1.850H − 4.676A
TDEE = BMR × activity factor
Worked example
Inputs: Sex: Male; Age: 30 years; Weight: 75 kg; Height: 178 cm; Activity level: Light – exercise 1–3 times a week.
Results: BMR – revised Harris–Benedict = 1,777 kcal/day; BMR – original Harris–Benedict = 1,786 kcal/day; Daily calories (TDEE) = 2,443 kcal/day; Mifflin–St Jeor BMR = 1,718 kcal/day.
Key terms
- BEE
- Basal energy expenditure, another name for BMR from Harris–Benedict.
Frequently asked questions
Why are there two Harris–Benedict equations?
The 1984 revision re-fitted the original data with modern statistics.
Which should I use?
The revised equation, or Mifflin–St Jeor, for most adults.
Does it work for obese people?
It tends to overestimate their needs; Mifflin–St Jeor is preferred.
Sources
- Mifflin MD et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr, 1990
- Roza AM, Shizgal HM. The Harris Benedict equation reevaluated. Am J Clin Nutr, 1984
- McArdle WD, Katch FI, Katch VL. Exercise Physiology: Nutrition, Energy and Human Performance
- Harris JA, Benedict FG. A biometric study of human basal metabolism. PNAS, 1918
Guides on this topic
- How Many Calories Should I Eat? BMR, TDEE and Your Real Number: Your calorie target starts with BMR and TDEE, but the real number comes from adjusting after a few weeks. A step-by-step method with a full worked example.