Harris-Benedict Calculator
A 32-year-old woman weighing 68 kg at 165 cm has an estimated BMR of about 1,449 calories a day and a TDEE near 2,246 calories with moderate activity. This Harris-Benedict calculator uses the revised 1984 Harris-Benedict equation and standard activity multipliers to estimate basal metabolic rate and total daily energy expenditure from your sex, age, height, weight, and typical activity level. The original Harris-Benedict equation dates to 1919 and was revised by Roza and Shizgal in 1984 using updated body-composition research. This calculator applies that revised version, then multiplies the resting estimate by a standard activity factor to project how many calories you burn across a full day, including exercise, walking, fidgeting, and digestion. Use the output as a starting reference point for weight management, not as a fixed prescription.
Quick answer
BMR estimates the calories your body burns at complete rest, just to keep organs, breathing, and circulation running.
What this tells you
- •BMR estimates the calories your body burns at complete rest, just to keep organs, breathing, and circulation running.
- •TDEE multiplies BMR by an activity factor to estimate the calories you burn across a full day, including exercise and daily movement.
- •This tool uses the revised 1984 Harris-Benedict equation from Roza and Shizgal, not the original 1919 version.
- •Five activity levels are available, from sedentary at 1.2 to extra active at 1.9, each scaling BMR by a different multiplier.
- •Sex, age, weight, and height each shift the BMR estimate, since resting metabolism varies with body size and hormonal differences.
- •The result is a planning estimate for calorie targets, not a diagnosis, lab measurement, or medical prescription.
How to Use
- 1Select your sex, since the Harris-Benedict formula uses separate equations for men and women.
- 2Enter your age in years and your current weight in kilograms.
- 3Enter your current height in centimeters.
- 4Choose the activity level that matches your average week, not your hardest or easiest day.
- 5Select Calculate to see your estimated BMR, TDEE, and the activity factor applied.
- 6Compare the TDEE estimate against real weight-trend data over two to three weeks before adjusting calorie intake.
How It Works
Formula
Men: BMR = 88.362 + 13.397W + 4.799H - 5.677A
Women: BMR = 447.593 + 9.247W + 3.098H - 4.330A
TDEE = BMR x activity factor
Factors used here: sedentary 1.2, light 1.375, moderate 1.55, very 1.725, extra 1.9W is weight in kilograms, H is height in centimeters, and A is age in years. This tool applies the revised Harris-Benedict equation published by Roza and Shizgal in 1984, which updated the original 1919 formula using more recent body-composition data. BMR is calculated first, then multiplied by a standard activity factor to estimate TDEE, the total number of calories the body uses across a full day. The equation assumes a typical body composition for a given weight and height, so it cannot separately account for how much of that weight is muscle versus fat.
Calculation note: values are processed in the order shown above, using the current input units.
Worked Examples
Moderately active female example
The revised Harris-Benedict formula gives the resting estimate first: 447.593 plus 9.247 times 68, plus 3.098 times 165, minus 4.33 times 32, comes to about 1,449 kcal. Multiplying by the moderate activity factor of 1.55 scales that to a full-day estimate near 2,246 kcal.
Sedentary male example
Using the men's equation, 88.362 plus 13.397 times 90, plus 4.799 times 178, minus 5.677 times 42, comes to roughly 1,910 kcal. A sedentary activity factor of 1.2 keeps TDEE close to BMR, which is common when structured exercise and daily movement are limited.
Very active male example
A younger, taller frame combined with the men's equation produces a BMR near 1,815 kcal. The very active factor of 1.725 pushes TDEE up to about 3,131 kcal, reflecting frequent hard training or a physically demanding job on top of daily movement.
Lightly active female example
Age lowers the estimate here, since the women's equation returns a BMR near 1,297 kcal at 45 years old. The light activity factor of 1.375 brings TDEE to roughly 1,783 kcal, typical for someone who exercises a few times a week.
Extra active male example
Even with a higher age reducing BMR, the extra active factor of 1.9 pushes TDEE up to roughly 3,176 kcal. This activity level fits physically demanding jobs combined with daily hard training, not a typical gym routine a few times a week.
Sedentary female example
A smaller frame combined with a sedentary lifestyle produces one of the lower TDEE estimates in this set, about 1,604 kcal. Anyone starting from a number this low should increase daily activity gradually rather than cutting calorie intake aggressively.
Activity Level Multipliers
Standard activity factors this calculator applies to BMR to estimate TDEE.
| Activity level | Multiplier | Typical description |
|---|---|---|
| Sedentary | 1.2 | Little or no exercise, mostly desk-based work |
| Lightly active | 1.375 | Light exercise or sports 1 to 3 days a week |
| Moderately active | 1.55 | Moderate exercise or sports 3 to 5 days a week |
| Very active | 1.725 | Hard exercise or sports 6 to 7 days a week |
| Extra active | 1.9 | Very hard daily training or a physically demanding job |
Choose the level that matches a typical week for you, not an unusually busy or unusually restful one.
Common mistakes
- Choosing an activity level based on your best workout week instead of your typical week
- Entering pounds as kilograms or inches as centimeters, which produces a badly skewed BMR
- Treating the estimated TDEE as an exact calorie prescription instead of a starting point
- Ignoring body composition, since two people with the same weight and height can have very different muscle mass and true metabolic rates
- Recalculating results every day, when weight and activity level typically only shift meaningfully every few weeks
- Using this calculator during pregnancy, active illness, or eating-disorder recovery, when standard formulas do not reliably apply
Limitations
This calculator uses population-level averages derived from body-composition research and cannot account for individual metabolic variation. It does not factor in body-fat percentage, muscle mass, pregnancy, menopause, illness, thyroid conditions, medications, or adaptive thermogenesis, all of which can shift real calorie needs above or below the estimate. The revised 1984 equation was built from research on a broad adult population, so results may be less reliable for people far outside typical body-composition ranges, including bodybuilders, endurance athletes, and people with very high or very low body fat. Activity factors are broad categories rather than measurements, so two people who both select moderately active can still have meaningfully different real-world energy expenditure. Treat the BMR and TDEE figures as a starting estimate to adjust using real weight-trend data, not as a fixed target.
Embed this calculator on your site
Drop this single line where you want the calculator to appear. It is responsive, mobile-friendly, resizes automatically, and is free to use with attribution.
<script src="https://calctide.com/embed.js" data-tool="harris-benedict-calculator" async></script>Preview the embed at /embed/harris-benedict-calculator/.