Estimate resting energy expenditure and daily calorie needs in kcal/day with the Harris-Benedict formula using sex, weight, height, age, and activity.
Disclaimer: This calculator provides an estimate only and is not medical advice or a diagnosis. Do not use it to set calorie intake for children/adolescents, pregnancy or breastfeeding, eating disorders, or medical conditions without guidance from a qualified clinician or registered dietitian.
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REE (Harris–Benedict) Resting Energy Expenditure Formula
The calculator uses the Harris-Benedict equations to estimate resting energy expenditure, commonly shown as BMR in the calculator. Weight is converted to kilograms and height is converted to centimeters before the equation is applied.
BMR_male = 66.47 + 13.75*W + 5*H - 6.76*A
BMR_female = 655.1 + 9.563*W + 1.85*H - 4.676*A
TDEE = BMR * Activity_Multiplier
kJ/day = kcal/day * 4.184
- BMR = basal metabolic rate or resting energy expenditure, in kcal/day
- TDEE = total daily energy expenditure, in kcal/day
- W = weight in kilograms
- H = height in centimeters
- A = age in years
- Activity_Multiplier = factor used to estimate daily calories after activity
- kcal/day = Calories per day, the main output
- kJ/day = kilojoules per day
In resting mode, the calculator returns the Harris-Benedict BMR estimate only. In daily total mode, it first calculates BMR, then multiplies that result by your selected activity level to estimate TDEE. If you enter pounds or inches, the calculator converts them before using the formula: pounds are multiplied by 0.453592 to get kilograms, and inches are multiplied by 2.54 to get centimeters.
Activity Multipliers Used for Daily Total Calories
When you choose daily total with activity, the BMR result is multiplied by one of these factors.
| Activity level | Multiplier | Use this when |
|---|---|---|
| Sedentary | 1.2 | You get little or no planned exercise. |
| Light | 1.375 | You exercise about 1 to 3 days per week. |
| Moderate | 1.55 | You exercise about 3 to 5 days per week. |
| Very active | 1.725 | You exercise hard most days. |
| Extra active | 1.9 | You do hard daily training or have a physically demanding job. |
Common Unit Conversions for REE Inputs
| Input | Conversion used | Example |
|---|---|---|
| Pounds to kilograms | kg = lb * 0.453592 | 170 lb = 77.1 kg |
| Inches to centimeters | cm = in * 2.54 | 68 in = 172.7 cm |
| Calories to kilojoules | kJ = kcal * 4.184 | 2,000 kcal = 8,368 kJ |
Example REE Calculations
Example 1: Male resting energy expenditure
Suppose you enter a male, 170 lb, 68 in, age 35.
First convert the inputs:
- Weight: 170 * 0.453592 = 77.1 kg
- Height: 68 * 2.54 = 172.7 cm
Use the male Harris-Benedict equation:
BMR = 66.47 + 13.75*77.1 + 5*172.7 - 6.76*35
The result is about 1,753 kcal/day.
Example 2: Female daily total with moderate activity
Suppose you enter a female, 65 kg, 165 cm, age 30, with moderate activity.
BMR = 655.1 + 9.563*65 + 1.85*165 - 4.676*30
BMR is about 1,441 kcal/day.
TDEE = 1441 * 1.55
The daily total is about 2,234 kcal/day.
FAQ
Is REE the same as BMR?
REE and BMR are often used in similar ways, but they are not exactly identical. BMR usually refers to energy used under stricter resting conditions, while REE is a resting estimate that may be measured under slightly less strict conditions. In this calculator, the resting result is based on the Harris-Benedict BMR equation and is used as an estimate of resting energy expenditure.
Why does activity level change the result so much?
Your resting energy expenditure estimates calories used at rest. Daily total energy expenditure includes additional calories from movement, exercise, work, and normal daily activity. That is why the daily total mode multiplies BMR by an activity factor. Choosing a higher activity level increases the estimate.
Should you use the resting result or the daily total result?
Use the resting result if you want an estimate of calories your body uses at rest. Use the daily total result if you want an estimate of calories needed to maintain body weight at your current activity level. For weight change planning, the daily total result is usually the more useful starting point.
