Harris-Benedict BMR Calculator – Basal Metabolic Rate
Calculate your Basal Metabolic Rate (BMR) and Total Daily Energy Expenditure (TDEE) using the Harris-Benedict equation for precise calorie planning.
Enter your weight, height, age, biological sex, and activity level to find out how many calories your body burns at rest and throughout the day.
Harris-Benedict BMR Calculator – Basal Metabolic Rate
Calculate your Basal Metabolic Rate (BMR) and Total Daily Energy Expenditure (TDEE) using the Harris-Benedict equation for precise calorie planning.
Harris-Benedict calculator examples
About the Harris-Benedict BMR calculator
Basal Metabolic Rate (BMR) is the number of calories your body requires to maintain basic life-sustaining functions — heartbeat, breathing, temperature regulation, and cellular repair — while completely at rest for a 24-hour period. It represents the energy floor below which intake should never fall for extended periods without medical supervision, and it is the starting point for virtually all evidence-based nutrition plans.
The Harris-Benedict equation, first published in 1919 by James Arthur Harris and Francis Gano Benedict, remains one of the most widely cited BMR formulas in clinical nutrition. The revised version published by Roza and Shizgal in 1984 corrected minor coefficients and is the variant used in this calculator. For males the formula is: BMR = 88.362 + (13.397 × weight in kg) + (4.799 × height in cm) − (5.677 × age in years). For females it is: BMR = 447.593 + (9.247 × weight in kg) + (3.098 × height in cm) − (4.330 × age in years). The separate equations reflect physiological differences in lean body mass distribution between biological sexes.
Total Daily Energy Expenditure (TDEE) multiplies BMR by an activity factor that accounts for energy burned through physical movement. The five standard activity multipliers are: Sedentary (×1.2, desk job with no formal exercise), Lightly Active (×1.375, light exercise one to three days per week), Moderately Active (×1.55, moderate exercise three to five days per week), Very Active (×1.725, hard exercise six to seven days per week), and Extra Active (×1.9, physically demanding job or training twice daily). Selecting the most honest activity category for your actual lifestyle is crucial because even one step up increases TDEE by roughly 175 kcal per day — equivalent to 18 lb of body fat per year.
The calculator also displays targets for weight loss and weight gain. A deficit of 500 kcal per day below TDEE typically produces approximately 0.45 kg (1 lb) of fat loss per week, a widely recommended moderate pace. A surplus of 500 kcal above TDEE supports muscle gain in people following a structured resistance-training programme, though a portion of any surplus is inevitably stored as fat.
It is important to understand the limitations of any predictive BMR equation. Harris-Benedict assumes average body composition for the given sex and age — it overestimates BMR for obese individuals (who carry more adipose tissue relative to metabolically active lean mass) and underestimates it for highly muscular people (who have more lean mass per unit of body weight). For more accurate results in those populations, alternatives such as the Mifflin–St Jeor equation or body-composition-based formulas like Katch-McArdle can be used. For the general population without extreme body composition, Harris-Benedict is accurate to within roughly 10–15% of true measured resting metabolic rate.
Calorie estimates from any equation are a starting point, not a fixed prescription. Individual metabolism varies with genetics, hormonal status, gut microbiome, sleep quality, and countless other factors. Use your calculated TDEE as a baseline, track your actual weight trend over two to four weeks, and adjust intake by 100–200 kcal per day in the direction needed to reach your goal.
Harris-Benedict calculator examples
Four typical profiles showing how weight, height, age, gender, and activity level translate into BMR and TDEE estimates.
| Profile | BMR / TDEE | Practical target |
|---|---|---|
| Male, 75 kg, 180 cm, 35 y, Sedentary | BMR 1,758 kcal / TDEE 2,110 kcal | Office worker. Weight-loss target: 1,610 kcal/day. Maintenance: 2,110 kcal/day. |
| Female, 60 kg, 165 cm, 25 y, Very Active | BMR 1,405 kcal / TDEE 2,424 kcal | Female athlete training daily. Higher TDEE means more room for food without gaining weight. |
| Male, 70 kg, 170 cm, 40 y, Moderately Active | BMR 1,615 kcal / TDEE 2,503 kcal | Adult with regular gym visits 3–5×/week. Weight-loss target: 2,003 kcal/day. |
| Female, 65 kg, 160 cm, 65 y, Lightly Active | BMR 1,263 kcal / TDEE 1,737 kcal | Elderly woman with light daily activity. Lower TDEE reflects age-related metabolic slowdown. |
How to use the Harris-Benedict calculator
- Enter your weight in kilograms and your height in centimetres — use a recent measurement rather than an estimate for the most accurate BMR.
- Enter your age in whole years and select your biological sex (Male or Female), as the Harris-Benedict equation uses different coefficients for each.
- Select the activity level that most honestly describes your typical week — when in doubt, choose the lower option to avoid overestimating calorie needs.
- Click Calculate to see your BMR, TDEE, and the adjusted targets for weight loss (−500 kcal) and weight gain (+500 kcal).
- Use your TDEE as a daily calorie target for maintenance, track your actual weight for two weeks, and adjust by 100–200 kcal if the scale is not moving as expected.
Harris-Benedict BMR calculator FAQ
What is the difference between BMR and TDEE?
BMR (Basal Metabolic Rate) is the calories your body needs to stay alive at complete rest — no movement, digestion, or activity beyond basic cellular function. TDEE (Total Daily Energy Expenditure) multiplies BMR by an activity factor to account for all movement during the day. To maintain weight, eat at your TDEE; to lose fat, eat below it; to gain muscle, eat above it.
How accurate is the Harris-Benedict equation?
Studies comparing Harris-Benedict predictions against indirect calorimetry (a laboratory gold standard) find mean errors of 10–15% in healthy adults of average build. Accuracy decreases for people with obesity (overestimated BMR) or very high muscle mass (underestimated BMR). The Mifflin–St Jeor equation, derived from a 1990 study, is sometimes preferred as marginally more accurate for the modern sedentary population.
Which activity level should I choose?
Choose Sedentary if you have a desk job and do not exercise. Choose Lightly Active if you walk or do light exercise one to three days per week. Choose Moderately Active for gym sessions or sports three to five days per week. Choose Very Active for daily hard training. Choose Extra Active only for elite athletes or workers doing heavy physical labour all day — most people overestimate their activity level, which leads to weight gain when eating at the calculated TDEE.
How many calories should I eat to lose 1 kg per week?
One kilogram of body fat represents approximately 7,700 kcal of stored energy. To lose 1 kg per week you need a deficit of 7,700 ÷ 7 ≈ 1,100 kcal per day, which most clinicians consider aggressive. A safer target is 0.5 kg per week (550 kcal daily deficit) or 0.25 kg per week (275 kcal deficit) for those close to a healthy weight. Do not eat below your BMR for extended periods without medical supervision.
Does BMR decrease with age?
Yes. BMR typically declines by roughly 1–2% per decade after age 20, primarily because lean body mass (muscle and organ tissue) decreases with age in the absence of strength training. The Harris-Benedict equation captures this through the age coefficient. Maintaining or building muscle through resistance exercise is the most effective way to preserve metabolic rate as you age.
Should I use my current weight or goal weight?
For an honest baseline, use your current weight — this reflects your actual metabolic needs right now. Using your goal weight will give you a target BMR to aim for but may underestimate current needs and create too large a deficit initially. Recalculate every 4–8 weeks as your weight changes, since every kilogram of body mass lost slightly lowers your TDEE and requires a new calorie target to maintain the same rate of progress.