Looking for a BMR calculator? This tool estimates resting energy expenditure (RMR/REE) with the Mifflin–St Jeor equation and total daily energy expenditure (TDEE) using the U.S. National Academies’ 2023 adult equations. The two results come from independent studies. Neither is a personal calorie prescription.
Use the blank weight and waist log to track measurements. Find other print forms in the health records library. The Print/PDF button above prints this calculation summary.
How are the two estimates different?
Resting energy expenditure estimates energy used for basic functions while awake and at rest. Mifflin–St Jeor predicts RMR/REE. Although often called “BMR” online, a basal metabolic rate measured under stricter conditions is a different measure.
Total daily energy expenditure includes resting needs, everyday movement, work and exercise, and the energy cost of processing food. This tool uses the 2023 Estimated Energy Requirement (EER) equations developed for the United States and Canada. For a weight-stable adult, EER is an estimate of TDEE. The daily result is not calculated by multiplying the displayed RMR by an exercise factor.
Equations and units
Mifflin–St Jeor RMR (kcal/day) = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) + the equation’s sex term: +5 for its male parameter or −161 for its female parameter. The original equation was derived from 498 healthy adults aged 19–78. Estimates above age 78 are outside that study’s age range.
The daily estimate uses Table S-3 of the National Academies’ 2023 adult (19+) equations, selecting one of eight coefficient sets by sex parameter and activity category. Its form is EER = intercept + age coefficient × age (years) + height coefficient × height (cm) + weight coefficient × weight (kg). The source table gives all eight coefficients. Displayed results are rounded to whole kcal/day.
Worked example using two separate equations
As an illustration, choose age 22, height 165 cm, weight 63 kg, the female equation parameter, and the ‘low active’ category. Each result comes from a different study equation.
| Estimate | Calculation and result |
|---|---|
| RMR | 10×63 + 6.25×165 − 5×22 − 161 = 1,390.25 → about 1,390 kcal/day |
| EER/TDEE | 575.77 − 7.01×22 + 6.60×165 + 12.14×63 = 2,275.37 → about 2,275 kcal/day |
The daily estimate is not RMR multiplied by an activity factor. Selecting another activity category changes the daily value. The 2023 equation was developed from U.S. and Canadian data; it is a population-based estimate rather than a validated personal calorie prescription for someone in Korea or elsewhere.
Choosing a daily activity category
“Inactive” still includes ordinary activities of daily living, such as some walking and light household tasks. “Low active” adds substantial movement; “active” and “very active” involve progressively more sustained activity. Consider your occupation, travel, chores, walking, and exercise together. The number of workout sessions alone cannot reliably determine a person’s activity category.
Is this my daily food target?
No. The estimate is a starting point that assumes stable body weight. People with the same age, height, weight, and broad activity category can have different actual needs. RMR is not a minimum food intake prescription, and the maintenance estimate is not a weight-loss or weight-gain plan. Discuss a personalized plan, health conditions, and weight trends over time with a qualified professional.
Who should not use this general adult estimate?
Energy needs in people younger than 19, during pregnancy, and during breastfeeding require different considerations or equations; this tool does not cover those situations. Acute or serious illness (such as critical care), muscle wasting from chronic disease, bariatric surgery, and medicines that change energy expenditure call for individual assessment. Severe fluid retention or limb amputation can also make measured weight a poor input for a general prediction equation. Athletes in prolonged strenuous training can exceed the equation’s activity range even at “very active.”
If you have an eating disorder or are concerned about restrictive eating, do not use these numbers as a food target; discuss nutrition with your care team or dietitian. RMR estimates above age 78 extrapolate beyond the original Mifflin–St Jeor study. The underlying research models used male and female sex terms. If neither parameter clearly fits your circumstances, ask a clinician or dietitian how to assess your energy needs.
Why might my actual energy use differ?
People with the same age, height, weight and broad activity category can expend different amounts of energy. The 2023 study reports differences between predicted and measured expenditure; the category is also difficult to determine from a weekly exercise count. Review sustained weight trends, activity and health context instead of treating an example value of 2,275 kcal as an exact daily food target.
For a separate look at waist measurements and central adiposity, see the waist-to-height ratio calculator. That ratio cannot calculate energy needs or body-fat mass.
Frequently asked questions
Why does this differ from a BMR × 1.2 estimate?
This daily value uses a separate 2023 EER equation rather than a fixed multiplier applied to Mifflin–St Jeor RMR. Neither method measures an individual’s actual expenditure.
Is the daily result an exact number of calories to eat?
No. Your selected activity category and person-to-person variation both affect accuracy. Monitoring weight and health over time is part of interpreting estimated maintenance needs.
Related tools and primary sources
Health calculators · Adult BMI calculator. BMI alone does not diagnose nutritional status or disease.
Mifflin et al.: original RMR study · National Academies 2023 energy equations (Table S-3) · Activity categories and interpretation · National Academies: prediction errors · NIDDK Body Weight Planner · NHS hospital: fluid changes and amputations in weight assessment · NIMH: eating disorders and individual care. Sources and examples checked by Life Choice Note, 26 September 2026. No independent physician review has been performed. This is general information, not a diagnosis or dietary prescription. Editorial standards · Disclaimer