How to use this calculator
- Choose your sex and enter age, height and weight. Your BMR appears as you type. Mifflin-St Jeor is the default equation. Switch units to use feet, inches and pounds.
- If you know your body fat percentage, add it. You will also see the Katch-McArdle result, which uses lean body mass, and you can make it the main equation.
- Pick your usual activity level to see TDEE, which is BMR multiplied by an activity factor (PAL). The table below adds the estimated energy requirement from the Korean Dietary Reference Intakes 2025.
What BMR means
Basal metabolic rate (BMR) is the energy your body uses at complete rest, awake and lying down, to breathe, keep warm and keep your heart beating. The FAO/WHO/UNU report on human energy requirements says BMR makes up about 45 to 70 percent of total daily energy expenditure in adults. Measuring it takes a lab: 10 to 12 hours after a meal, after 8 hours of physical rest, with indirect calorimetry. That is why most people use an equation based on height, weight and age.
Strictly speaking, the equations below estimate resting energy expenditure (REE). REE is measured under slightly less strict conditions than BMR, but in everyday use the two terms mean almost the same thing.
The three equations
Mifflin-St Jeor (1990) was built from 498 healthy adults aged 19 to 78, including 264 of normal weight and 234 with obesity. The paper reported that the original 1919 Harris-Benedict equations overestimated measured REE by 5%. It is the default here.
Men = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5
Women = 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161
Revised Harris-Benedict (Roza and Shizgal, 1984) recalculated the coefficients using Harris and Benedict's original data plus subjects Benedict published later. The authors state it estimates the REE of a healthy person with a precision of about 14%.
Men = 88.362 + 13.397 × weight + 4.799 × height − 5.677 × age
Women = 447.593 + 9.247 × weight + 3.098 × height − 4.330 × age
Katch-McArdle uses only lean body mass. It has the same coefficients as the general equation Cunningham proposed in 1991 after reviewing many studies. It can suit people whose muscle mass is well above or below average, but only if the body fat figure is accurate.
Lean mass (kg) = weight × (1 − body fat % ÷ 100)
BMR = 370 + 21.6 × lean mass
In pounds and inches, the calculator converts to kilograms (1 lb = 0.45359237 kg) and centimetres (1 in = 2.54 cm) first.
TDEE and activity factors
Daily energy use is estimated by multiplying BMR by a physical activity level (PAL), which is total daily energy expenditure divided by BMR. This calculator uses the lifestyle groups in Table 5.3 and the worked values in Table 5.1 of the FAO/WHO/UNU report Human energy requirements (2004).
| Activity level | PAL range | Value used |
|---|---|---|
| Sedentary or light | 1.40–1.69 | 1.53 |
| Active or moderately active | 1.70–1.99 | 1.76 |
| Vigorous | 2.00–2.40 | 2.25 |
The report notes that PAL values above 2.40 are hard to keep up for long. If your routine sits near the top or bottom of a range, choose "Enter my own" and type a value from 1.4 to 2.4. The common 1.2 to 1.9 multipliers seen elsewhere are not from this report, so they are not used here.
Korean DRI 2025 estimated energy requirement
The Korean Dietary Reference Intakes 2025, published in December 2025 by the Ministry of Health and Welfare and the Korean Nutrition Society, set the estimated energy requirement (EER) with the US Institute of Medicine equations and Korean reference body sizes. For adults the equations are below, with "low active" as the default level.
Men = 662 − 9.53 × age + PA × (15.91 × weight + 539.6 × height (m))
Women = 354 − 6.91 × age + PA × (9.36 × weight + 726 × height (m))
Adult PA coefficients are 1.11 (men) and 1.12 (women) for low active, 1.25 and 1.27 for active, and 1.48 and 1.45 for very active. "For your body" puts your height and weight into these equations. "Age-group value" is the final figure from Table 16, rounded to 100 kcal. For men aged 19 to 29 the low-active value was set at 2,600 kcal with obesity rates in mind.
| Age | Men | Women |
|---|---|---|
| 19–29 | 2,600 · 2,900 · 3,400 | 2,000 · 2,300 · 2,600 |
| 30–49 | 2,500 · 2,800 · 3,200 | 1,900 · 2,200 · 2,500 |
| 50–64 | 2,200 · 2,500 · 2,900 | 1,700 · 2,000 · 2,300 |
| 65–74 | 2,000 · 2,300 · 2,800 | 1,600 · 1,800 · 2,100 |
| 75 and over | 1,900 · 2,200 · 2,600 | 1,500 · 1,700 · 2,000 |
The Korean DRI says the active and very active values should only be used after assessing your activity level. During pregnancy add 340 kcal in the second trimester and 450 kcal in the third; during breastfeeding add 340 kcal. The Korean DRI activity levels and the FAO groups are defined differently, so the two numbers will not always match.
Worked examples
| Person | Mifflin | Harris-Benedict | TDEE (Mifflin) |
|---|---|---|---|
| Man, 30, 175 cm, 70 kg | 1,649 | 1,696 | 2,523 (× 1.53) |
| Woman, 25, 160 cm, 55 kg | 1,264 | 1,344 | 2,225 (× 1.76) |
| Man, 50, 170 cm, 75 kg | 1,568 | 1,625 | 2,398 (× 1.53) |
For the first example, 10 × 70 + 6.25 × 175 − 5 × 30 + 5 = 1,648.75, shown as 1,649 kcal. At 18% body fat, lean mass is 57.4 kg and Katch-McArdle gives 370 + 21.6 × 57.4 = 1,610 kcal. The Korean DRI low-active equation gives about 2,660 kcal for the same man.
Not for anyone under 19
All three equations were developed in adults, and children and teens need extra energy to grow. For ages under 19 the calculator does not compute BMR. For ages 6 to 18 it shows the Korean DRI 2025 age-group values instead; for ages 15 to 18 the low-active values are 2,700 kcal for boys and 2,000 kcal for girls. A pediatrician can check a child's needs against a growth chart.
Reading your result
- Equation results are close to the average for people of the same size. Your real metabolism can be higher or lower because of muscle mass, hormones and health.
- This calculator does not set a weight-loss target or a diet. If you want to change your weight, plan it with a doctor or dietitian.
- Do not rely on the numbers during thyroid disease, pregnancy, breastfeeding or recovery from illness, when metabolism changes.
- To check weight status as well, try the BMI calculator with WHO and Asian cut-offs.
Sources
- Mifflin MD, St Jeor ST, et al. A new predictive equation for resting energy expenditure in healthy individuals (Am J Clin Nutr 1990;51(2):241-247)
- Roza AM, Shizgal HM. The Harris Benedict equation reevaluated: resting energy requirements and the body cell mass (Am J Clin Nutr 1984;40(1):168-182)
- Cunningham JJ. Body composition as a determinant of energy expenditure: a synthetic review and a proposed general prediction equation (Am J Clin Nutr 1991;54(6):963-969)
- FAO/WHO/UNU, Human energy requirements (2004), chapter 5: Energy requirements of adults (Tables 5.1 and 5.3)
- Ministry of Health and Welfare (Korea), Dietary Reference Intakes for Koreans 2025 (Korean; volume 1, Tables 2, 12 and 16)
- The Korean Nutrition Society, KDRIs 2025 files (Korean)
Frequently asked questions
How is BMR calculated?
With Mifflin-St Jeor, men: 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5. Women use −161 instead of +5. A 30-year-old man at 175 cm and 70 kg gets 1,649 kcal/day.
Which BMR equation is most accurate?
Every equation has some error. This calculator uses Mifflin-St Jeor by default; its authors found the original Harris-Benedict equations overestimated measured REE by 5%. Katch-McArdle can help if your body fat figure is accurate.
What is the difference between BMR and TDEE?
BMR is the energy used at complete rest. TDEE estimates all the energy you use in a day, BMR multiplied by an activity factor (PAL) such as 1.53, 1.76 or 2.25.
Where do the activity factors come from?
From the FAO/WHO/UNU report Human energy requirements (2004): sedentary or light 1.40–1.69, active 1.70–1.99, vigorous 2.00–2.40, with worked values of 1.53, 1.76 and 2.25.
Can teenagers use a BMR calculator?
Adult equations are not meant for anyone under 19. The calculator shows Korean DRI 2025 age-group energy requirements for ages 6 to 18 instead.
Will eating my TDEE make me lose weight?
No result here is a weight-loss promise. These are estimates; plan any weight change with a doctor or dietitian.