The Harris-Benedict calculator applies the historic 1919 formula to estimate your basal metabolic rate (BMR) — the calories your body burns at complete rest. While we recommend the modern Mifflin-St Jeor calculator for everyday use, understanding the Harris-Benedict method is valuable for interpreting older research, clinical contexts, and the history of calorie science.
How to use the Harris-Benedict calculator
The Harris-Benedict calculator uses four inputs: weight, height, age, and sex. The steps are:
- Enter your weight in kilograms (or pounds, if using the original imperial formula).
- Enter your height in centimeters (or inches).
- Enter your age in years.
- Select your sex — men and women use different constants.
- Apply an activity multiplier to convert BMR into TDEE.
The Harris-Benedict formula (metric)
For men:
BMR = 88.362 + 13.397 × weight(kg) + 4.796 × height(cm) − 5.677 × age
For women:
BMR = 447.593 + 9.247 × weight(kg) + 3.098 × height(cm) − 4.330 × age
Step-by-step calculation example
A 30-year-old man, 180 cm, 80 kg:
Step 1: BMR = 88.362 + 13.397 × 80 + 4.796 × 180 - 5.677 × 30 BMR = 88.362 + 1,071.76 + 863.28 - 170.31 = 1,853.1 calories/day
With moderate activity (1.55): 1,853.1 × 1.55 = 2,872 calories/day maintenance.
Comparison with Mifflin-St Jeor
Using the same inputs with Mifflin-St Jeor:
BMR = 10 × 80 + 6.25 × 180 - 5 × 30 + 5 BMR = 800 + 1,125 - 150 + 5 = 1,780 calories/day
Mifflin-St Jeor predicts a BMR of 1,780 versus Harris-Benedict's 1,853 — a difference of 73 calories. That may not sound like much, but multiplied by 30 days it is 2,190 calories, or more than half a pound of fat.
When to use each formula
| Scenario | Recommended formula |
|---|---|
| Everyday calorie planning | Mifflin-St Jeor |
| Historical research comparison | Harris-Benedict |
| Clinical or hospital protocol | Check with your care team |
| Very elderly patients | Revised Harris-Benedict or clinician judgment |
| Online calculator / quick estimate | Mifflin-St Jeor |
Practical guidance
If you are using Harris-Benedict because you want to double-check an older result, follow these tips:
- Track your weight for 2–3 weeks at your calculated intake.
- If you are gaining weight, your true maintenance is probably lower than Harris-Benedict predicts. Subtract 100–200 calories.
- If you are losing weight faster than expected, your maintenance may be closer to the Mifflin-St Jeor estimate. Consider switching to the TDEE calculator.
- Do not run large deficits based on Harris-Benedict alone. The overestimation can lead to aggressive, unsustainable deficits.
Activity multipliers with Harris-Benedict
Once you have your Harris-Benedict BMR, apply the same activity multipliers used with Mifflin-St Jeor:
| Level | Multiplier |
|---|---|
| Sedentary | 1.2 |
| Lightly active | 1.375 |
| Moderately active | 1.55 |
| Very active | 1.725 |
| Extra active | 1.9 |
Links to related tools
- BMR calculator — uses Mifflin-St Jeor, the modern standard
- TDEE calculator — calculates maintenance calories accurately
- Harris-Benedict Equation — full historical context and formulas
- BMR equations comparison — all major formulas side by side
Sources and further reading
These independent, authoritative sources inform the methods used on this page.