Free harris-benedict calculator
See how many calories your body burns using the Harris-Benedict equation. Enter your weight, height, age, and sex and the calculator returns your basal metabolic rate from the revised 1984 formula, plus your daily calorie needs at every activity level — updated live, as you type.
On this page14 sections
| Activity | × | Calories / day |
|---|---|---|
| Sedentary · little or no exercise | 1.2 | 2,115 cal/day |
| Lightly active · 1–3 days/week | 1.375 | 2,424 cal/day |
| Moderately active · 3–5 days/week | 1.55 | 2,732 cal/day |
| Very active · 6–7 days/week | 1.725 | 3,041 cal/day |
| Athlete · twice daily / physical job | 1.9 | 3,349 cal/day |
BMR is an estimate; individual metabolism varies. How accurate is this?
Results are estimates. Consult a professional.
How the Harris-Benedict calculator works
The Harris-Benedict equation estimates your basal metabolic rate (BMR) — the calories your body burns at complete rest, just to keep you alive — and then turns that resting figure into your total daily energy expenditure (TDEE), the calories you actually burn once daily activity is added in. The calculator takes four inputs: your sex, weight, height, and age. It runs them through the revised Harris-Benedict equation, multiplies the result by an activity factor that matches how active your week is, and returns both your BMR and your daily calorie needs at every activity level.
What the number means
Your BMR is the floor of your energy use — the calories you would burn lying still for a full day, fasted and at rest. It is not how much you should eat, because almost nobody is motionless for 24 hours. Standing, walking, working, and training all stack on top of it. That total — BMR plus everything you do — is your TDEE, and it is the figure to use when you set a daily calorie target to lose, gain, or maintain weight.
What is the Harris-Benedict equation?
The Harris-Benedict equation is one of the oldest and most widely used formulas for predicting basal metabolic rate from a person's sex, weight, height, and age. It was first published in 1919 by James Arthur Harris and Francis Gano Benedict at the Carnegie Institution of Washington, and for roughly seventy years it was the default BMR formula in nutrition and medicine. The equation you see on most calculators today — including this one — is the revised version published in 1984 by Roza and Shizgal, which re-fit the original coefficients to a larger, more representative sample of people.
The equation works because resting metabolism scales predictably with body size, sex, and age. A bigger body has more tissue to maintain, so it burns more energy at rest. Men, on average, carry more lean muscle than women of the same weight, so the men's equation sits higher. And metabolism slowly declines with age as muscle mass falls — which is why age is subtracted. The Harris-Benedict equation simply puts numbers on those relationships.
Original (1919) vs revised (1984) Harris-Benedict
There are two Harris-Benedict equations, and it matters which one a calculator uses. The original 1919 formula was built from the body measurements available a century ago; the 1984 revision by Roza and Shizgal recalculated every coefficient against a broader dataset, correcting a tendency of the original to overestimate. This calculator uses the revised 1984 equation, which is the version clinicians and dietitians reach for today.
| Version | Men's BMR | Women's BMR |
|---|---|---|
| Original (1919) | 66.473 + 13.752×kg + 5.003×cm − 6.755×age | 655.096 + 9.563×kg + 1.850×cm − 4.676×age |
| Revised (1984) | 88.362 + 13.397×kg + 4.799×cm − 5.677×age | 447.593 + 9.247×kg + 3.098×cm − 4.330×age |
The revised 1984 coefficients (Roza & Shizgal) are the ones this calculator applies.
BMR vs TDEE: turning resting burn into daily calories
Your BMR is your calorie burn at rest. Total daily energy expenditure (TDEE) is what you actually burn once moving, working, digesting, and exercising are counted — and TDEE, not BMR, is the number that tells you how much to eat. To get there, you multiply your Harris-Benedict BMR by an activity factor that matches a typical week. The busier your days, the higher the multiplier, and the further your real needs sit above your resting floor.
| Activity level | Multiplier | What it means |
|---|---|---|
| Sedentary | 1.2 | Desk job, little or no exercise |
| Lightly active | 1.375 | Light exercise or sport 1–3 days a week |
| Moderately active | 1.55 | Moderate exercise 3–5 days a week |
| Very active | 1.725 | Hard exercise or sport 6–7 days a week |
| Athlete | 1.9 | Twice-daily training or a physical job plus exercise |
Standard activity factors paired with the Harris-Benedict equation to estimate TDEE. TDEE = BMR × activity factor.
Pick the level that matches a normal week, not your best one — most people overestimate. For a deeper breakdown of your daily needs, the TDEE calculator and calorie calculator build on the same figures shown here.
A worked example using the Harris-Benedict calculator
Daniel is 30, stands 175 cm, and weighs 75 kg. He wants his resting calorie burn and his daily needs. Here is the arithmetic the calculator runs through the men's revised (1984) Harris-Benedict equation.
Step 1 — Weight and height terms
13.397 × 75 = 1,004.78, and 4.799 × 175 = 839.83.
Step 2 — Age term and the male constant
5.677 × 30 = 170.31, which is subtracted, and the men's equation starts from a constant of 88.362.
Step 3 — Add it all up for BMR
88.362 + 1,004.78 + 839.83 − 170.31 = 1,762.65, which rounds to about 1,763 calories a day at complete rest.
Step 4 — Multiply by activity for TDEE
Harris-Benedict vs Mifflin-St Jeor: which is more accurate?
The Harris-Benedict equation is reliable, but it is no longer considered the most accurate of the common BMR formulas. When the American Dietetic Association reviewed the major predictive equations, the Mifflin-St Jeor equation (1990) came out ahead, predicting resting energy expenditure within 10% of measured values more often than Harris-Benedict did. The Harris-Benedict equation — even the 1984 revision — tends to run slightly high for modern populations, because it was built from samples that were leaner and more active on average than people today.
| Harris-Benedict (revised 1984) | Mifflin-St Jeor (1990) | |
|---|---|---|
| Men's formula | 88.362 + 13.397×kg + 4.799×cm − 5.677×age | 10×kg + 6.25×cm − 5×age + 5 |
| Women's formula | 447.593 + 9.247×kg + 3.098×cm − 4.330×age | 10×kg + 6.25×cm − 5×age − 161 |
| Same man, 75kg/175cm/30yr | ≈ 1,763 cal | ≈ 1,699 cal |
| Accuracy | Tends to overestimate slightly | Most accurate per the ADA |
Both estimate BMR from the same four inputs; Mifflin-St Jeor is the modern first choice, Harris-Benedict the long-standing classic.
So why use Harris-Benedict at all? It is the historical reference many programs, textbooks, and clinical protocols are still built around, and for most people the two formulas land within about 50–100 calories of each other. If you want the modern standard, see the BMR calculator, which uses Mifflin-St Jeor. Whichever you choose, the result is an estimate — the only way to measure your true resting burn is lab indirect calorimetry.
Using your Harris-Benedict result for weight goals
Once you have your TDEE, setting a calorie target is simple arithmetic. Maintenance is your TDEE. To lose weight, you eat below it; to gain, above it. A pound of fat is roughly 3,500 calories, so a 500-calorie daily deficit loses about a pound a week — a sustainable, widely used target.
- To lose weight — subtract 250–500 calories a day from your TDEE for steady fat loss of about half a pound to a pound a week.
- To maintain weight — eat at your TDEE; that is the figure the calculator returns at your activity level.
- To gain weight or muscle — add 250–500 calories a day to your TDEE for a lean, controlled gain.
Then refine against reality. The equation is a starting point built from population averages; your scale over two to three weeks is the real test. If your weight is not moving the way the numbers predict, adjust intake by 100–200 calories rather than assuming the formula is exact. The calorie deficit calculator works the deficit out for you.
What affects your BMR
Two people of the same age, height, and weight can have noticeably different resting burns. The Harris-Benedict equation captures the average relationships, but several factors push an individual's BMR up or down:
- Muscle mass — lean muscle burns more calories at rest than fat, so a more muscular body has a higher BMR. It is the factor you can most change, through resistance training.
- Body size — a larger body has more tissue to maintain, so taller and heavier people generally have a higher BMR.
- Age — BMR tends to fall through adulthood as muscle mass declines and body fat rises, which is why the equation subtracts an age term.
- Sex — men usually have a higher BMR than women of the same size, reflecting their larger average share of muscle.
- Genetics and hormones — inherited differences and thyroid function set the metabolic pace; an underactive thyroid lowers BMR, an overactive one raises it.
Formula and sources
This calculator uses the revised Harris-Benedict equation (Roza & Shizgal, 1984) for BMR and the standard activity factors (1.2 sedentary to 1.9 very active) to estimate TDEE. The original equation comes from Harris J.A. and Benedict F.G., A Biometric Study of Basal Metabolism in Man (Carnegie Institution of Washington, 1919). The accuracy comparison with Mifflin-St Jeor reflects the American Dietetic Association's review of predictive resting-energy equations.
Roza A.M., Shizgal H.M., "The Harris Benedict equation reevaluated" (American Journal of Clinical Nutrition, 1984).Frequently asked questions about the free harris-benedict calculator
About this Harris-Benedict calculator
This Harris-Benedict calculator runs entirely in your browser. Your weight, height, age, and sex never leave your device — nothing is sent to a server, logged, or shared. It uses the revised Harris-Benedict equation (Roza & Shizgal, 1984) for BMR and multiplies by standard activity factors (1.2 to 1.9) to estimate your daily calorie needs, updating instantly.
Calculators Cloud offers 400+ free tools with no sign-up. The whole Health calculators shelf includes BMR (Mifflin-St Jeor), TDEE, and calorie tools alongside this one. Or browse the full calculator directory.