BEE Calculator
Basal Energy Expenditure — clinical and fitness formula comparison with stress factor module
Age in years. Must be between 15 and 120.
Body weight in your selected unit system
Standing height in your selected unit system
Required for Katch-McArdle formula. Leave blank to skip. Most accurate for athletes.
For clinical/hospital use. Select the patient's condition to apply appropriate metabolic stress multiplier.
Each 1°C above 37°C adds ~7% to BEE. Enter 37 for no fever.
Enter Your Details
Fill in your sex, age, weight, and height to calculate your Basal Energy Expenditure using all major clinical formulas.
How to Use the BEE Calculator
Enter Your Basic Measurements
Select your sex, enter your age in years, and choose between metric (kg, cm) or imperial (lbs, ft/in) units. Enter your current weight and height. These inputs drive all five BEE formulas. For athletes or lean individuals who know their body fat percentage, enter it in the optional Body Fat field to unlock the Katch-McArdle formula.
Select Your Activity Level
Choose the activity level that best describes your typical week. This multiplier converts your BEE into Total Energy Expenditure (TEE) — the number of calories your body actually burns accounting for daily movement. Sedentary (desk job, little exercise) uses a multiplier of 1.2; Extra Active (intense daily training plus physical work) uses 1.9. For clinical hospital patients, use the clinical activity options (Bedrest or Ambulating) in the stress factor section.
Apply Clinical Stress Factors (Healthcare Professionals)
If calculating caloric requirements for a clinical patient, select the appropriate stress factor condition from the dropdown. This includes categories for infection, surgery, trauma, burns (classified by percentage of total body surface area), sepsis, and cancer. Optionally enter the patient's temperature to apply the fever factor. The tool will calculate the full clinical caloric requirement as BEE × activity factor × stress factor × fever factor.
Review All Formula Results and Charts
The results panel displays your BEE from all applicable formulas side by side, with a horizontal bar chart for quick visual comparison. The TEE breakdown donut chart shows how BEE, activity, and stress/fever increments combine into your total caloric requirement. Review estimated nutrient targets (protein, carbs, fat) based on your caloric needs. Use the Print button to generate a clean clinical summary, or Export CSV to download all formula values for documentation.
Frequently Asked Questions
What is the difference between BEE and BMR?
BEE (Basal Energy Expenditure) and BMR (Basal Metabolic Rate) refer to the same physiological concept — the minimum calories your body needs at complete rest — but they come from different professional traditions. BMR is the term used in fitness, wellness, and nutrition apps. BEE is the clinical and medical term used by registered dietitians, physicians, and ICU clinicians when calculating total parenteral nutrition (TPN), enteral feeding rates, and metabolic support for hospitalized patients. Both use the same Harris-Benedict equations. The practical difference is that BEE is always presented in the context of activity and stress factor multipliers that are used in clinical nutrition protocols, while BMR is more commonly multiplied by fitness-oriented activity factors to calculate TDEE for weight management.
Which BEE formula is most accurate?
For the general adult population, the Mifflin-St Jeor equation (1990) is the most accurate, predicting resting metabolic rate within plus or minus 10 percent for approximately 82 percent of subjects. It is recommended by the Academy of Nutrition and Dietetics as the preferred formula. The Katch-McArdle (Cunningham) formula is more accurate for athletes and lean individuals when an accurate body fat percentage is available, because it uses lean body mass rather than total body weight. The Harris-Benedict Revised (1984, Roza-Shizgal) is commonly used in clinical settings and is more accurate than the original 1919 version, particularly for obese patients. The Schofield equations are preferred in UK NHS clinical practice and for pediatric patients. No formula replaces measured indirect calorimetry, which is the gold standard.
How are clinical stress factors used in practice?
Clinical stress factors are multipliers applied to BEE to account for the hypermetabolic response to illness, injury, and critical conditions. The formula is: Total Caloric Requirement = BEE × Activity Factor × Stress Factor. A trauma patient on bedrest with multiple injuries might have a total requirement of BEE × 1.2 × 1.45, meaning their metabolic needs are 74 percent above their resting BEE. Stress factors are primarily used when calculating TPN (intravenous nutrition) or tube-feeding rates for patients who cannot eat normally. Values range from 1.0 for healthy adults to 2.0 for severe burns. Modern ASPEN and ESPEN guidelines note that indirect calorimetry is preferred over calculated values in critically ill patients, as stress factor accuracy varies widely between individuals.
What does the fever temperature factor do?
Fever increases the body's metabolic rate by approximately 7 percent per degree Celsius above 37°C (or about 13 percent per degree Fahrenheit above 98.6°F). This is because elevated body temperature accelerates all biochemical reactions. For example, a patient with a fever of 39°C has a temperature factor of 1.14, meaning their BEE is 14 percent higher than at normal temperature before accounting for activity or stress. In clinical nutrition, fever is treated as a separate multiplicative factor alongside activity and stress: Total Caloric Requirement = BEE × Activity Factor × Stress Factor × Temperature Factor. For patients without fever (normal temperature of 37°C), the temperature factor equals 1.0 and has no effect on the calculation.
How do I use BEE results for weight management?
For weight management, use the Total Energy Expenditure (TEE) as your maintenance calorie level. To lose weight, create a caloric deficit of 300 to 500 calories below your TEE, which produces a safe rate of 0.5 to 1 pound of fat loss per week. To gain muscle mass, eat 250 to 500 calories above your TEE while engaging in progressive resistance training. Avoid deficits greater than 1000 calories per day, which can cause muscle loss and metabolic adaptation. Note that the BEE itself changes as your body weight and composition change, so recalculate every 4 to 6 weeks if you are actively losing or gaining weight. The Mifflin-St Jeor formula is recommended for general weight management use.
Why does my BEE differ between formulas?
Each formula was developed from a different study population using different regression methods, which is why results vary. The original Harris-Benedict (1919) was derived from only 239 subjects and tends to overestimate BEE in obese individuals by up to 36 percent. The Mifflin-St Jeor (1990) used 498 subjects and is more accurate for today's diverse population. Katch-McArdle bypasses gender-based weight coefficients entirely by using lean body mass, which gives very different results for people with unusual body compositions. Formula differences of 5 to 10 percent are normal. Differences greater than 15 percent usually indicate that one formula is more appropriate for your specific profile — for example, Katch-McArdle for athletes or Schofield for elderly individuals. Use the formula comparison chart to understand the range of estimates and make an informed choice.