TDEE Formulas Compared: Which BMR Equation Is Most Accurate?
Six equations, the same two people, and what the research says about each one: Mifflin-St Jeor, revised Harris-Benedict, Katch-McArdle, Cunningham, Schofield and Oxford (Henry).
For most adults, the Mifflin-St Jeor equation is the best default. A 2005 systematic review for the American Dietetic Association compared the four equations most used in clinical practice and found Mifflin-St Jeor predicted resting metabolic rate within 10% of the measured value in more people, both with and without obesity, than any other equation, with the narrowest error range (Frankenfield et al., 2005). If you have a reliable body-fat figure and train regularly, a lean-mass equation such as Cunningham or Katch-McArdle can fit better. Every formula is an estimate, and your activity multiplier usually moves TDEE more than your choice of equation.
How a TDEE Formula Works
No equation calculates total daily energy expenditure (TDEE) in one step. Each one estimates your energy use at rest, and a calculator then multiplies that figure by an activity factor:
So "which TDEE formula is best" is really two questions: which resting equation to use, and which activity multiplier fits your week. The equations below answer the first. The activity section further down answers the second, and it is usually the bigger source of error.
BMR or RMR: Basal metabolic rate (BMR) is measured under strict conditions: lying still, fasted, after a night's sleep. Resting metabolic rate (RMR, also called resting energy expenditure) is measured with fewer restrictions and usually reads a little higher. Mifflin-St Jeor and Cunningham's 1991 equation were built from resting energy expenditure, while Harris-Benedict, Schofield and the Oxford equations describe basal metabolism. Calculators, including the BMR calculator on this site, label all of them "BMR", and the difference is small next to the error of any one equation.
The Six Equations and Where They Came From
1. Mifflin-St Jeor (1990)
Best DefaultBuilt from 498 healthy adults aged 19 to 78 (247 women, 251 men), about half of them with obesity, whose resting energy expenditure was measured by indirect calorimetry. In the same study, the original 1919 Harris-Benedict equations overestimated measured values by about 5% (Mifflin et al., 1990).
Women: (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161
In pounds and inches: (4.536 × weight in lb) + (15.875 × height in in) − (5 × age), then + 5 for men or − 161 for women
- Strengths: The 2005 review's most reliable equation for adults with and without obesity.
- Limitations: It cannot see body composition. The review also found older adults and US ethnic minorities underrepresented in the studies, so errors for those groups are less well known.
2. Harris-Benedict (1919, revised 1984)
Historical BenchmarkJames Harris and Francis Benedict published their equations from calorimetry on 239 adults in 1918 to 1919. Roza and Shizgal refit them in 1984 with additional subjects and reported a precision of about ±14% for well-nourished people (Roza & Shizgal, 1984). Most calculators that say "Harris-Benedict" use the 1984 version.
Revised, women: 447.593 + (9.247 × kg) + (3.098 × cm) − (4.330 × age)
Original, men: 66.5 + (13.75 × kg) + (5.003 × cm) − (6.755 × age)
Original, women: 655.1 + (9.563 × kg) + (1.850 × cm) − (4.676 × age)
- Strengths: Long track record; still printed in many clinical references.
- Limitations: Reads higher than Mifflin-St Jeor for most people. On the 28-year-old man below, the original gives about 1,799 kcal and the revision 1,788 kcal, against 1,728 kcal from Mifflin-St Jeor.
3. Katch-McArdle (Cunningham 1991)
Needs Body Fat %The equation known as Katch-McArdle is the general formula Cunningham proposed in a 1991 review of lean-mass studies, which he reported explained 65% to 90% of the variation in resting energy expenditure (Cunningham, 1991). McArdle, Katch and Katch's exercise physiology textbooks made it widely known, which is how it got its name. It uses lean body mass and ignores age, sex and fat mass.
Lean body mass = weight in kg × (1 − body fat % ÷ 100)
- Strengths: Tracks the tissue that drives resting burn. In one Scottish study of 150 adults, fat-free mass explained 63% of the differences in BMR between people (Johnstone et al., 2005).
- Limitations: Only as good as the body-fat number. A tape estimate or a bathroom scale can be off by several percentage points, which moves the result.
4. Cunningham (1980)
Lean Mass, Higher ConstantCunningham's first equation came from reanalysing 223 adults in the original Harris-Benedict data and finding lean body mass was the single best predictor (Cunningham, 1980). It was not built from athletes. Its athletic reputation comes from later testing: in 90 recreational athletes training about nine hours a week, Cunningham predicted resting energy expenditure well, while Harris-Benedict, WHO, Schofield, Mifflin-St Jeor and Owen were each within 10% for fewer than half of them (ten Haaf & Weijs, 2014).
- Strengths: The best-supported option here for regularly training adults aged roughly 18 to 35 with a measured body-fat figure.
- Limitations: Gives the highest number of the six for most people, so it can overshoot for someone who rarely trains.
5. Schofield / WHO (1985)
Weight and Age BandSchofield's equations were adopted by the 1985 FAO/WHO/UNU expert consultation and kept in its 2004 report on human energy requirements. They use only weight, within an age band. Henry later noted that 47% of the people behind them were Italian, and that they overestimate BMR in many populations (Henry, 2005).
| Age | Men (kcal/day) | Women (kcal/day) |
|---|---|---|
| 18–30 | 15.057 × kg + 692.2 | 14.818 × kg + 486.6 |
| 30–60 | 11.472 × kg + 873.1 | 8.126 × kg + 845.6 |
| 60+ | 11.711 × kg + 587.7 | 9.082 × kg + 658.5 |
- Strengths: Needs only weight, age and sex. Still the WHO reference equations.
- Limitations: Ignores height, and jumps at age-band boundaries.
6. Oxford / Henry (2005)
UK and EU ReferenceHenry rebuilt the Schofield database without the Italian subjects and with far more people from the tropics, 10,552 BMR measurements in all. The Oxford equations generally give lower values than Schofield for men aged 18 to 60 and for women over 18 (Henry, 2005). The UK Scientific Advisory Committee on Nutrition adopted them for its 2011 energy reference values, and the European Food Safety Authority used them in 2013.
- Strengths: The broadest data set of any equation here, and the current UK and EU reference.
- Limitations: Like Schofield, it works in age bands. It is not on this site's calculators.
Side-by-Side Comparison
| Equation | Inputs | Built from | What testing shows | Use it when |
|---|---|---|---|---|
| Mifflin-St Jeor | Weight, height, age, sex | 498 US adults, 1990 | Most often within 10% in the 2005 review | You have no body-fat figure (most people) |
| Harris-Benedict (revised) | Weight, height, age, sex | 1919 data, refit 1984 | Reads higher than Mifflin-St Jeor | You need to match an older plan or reference |
| Katch-McArdle | Lean body mass | Cunningham's 1991 review | Depends on body-fat accuracy | You have a reliable body-fat figure |
| Cunningham | Lean body mass | 223 adults, 1980 reanalysis | Accurate in 90 recreational athletes (2014) | You train often and know your body fat |
| Schofield / WHO | Weight, age band, sex | 7,173 people, 47% Italian | Overestimates in many populations | You follow WHO-based guidance |
| Oxford / Henry | Weight, age band, sex | 10,552 measurements, 2005 | UK and EU reference since 2011 | You follow UK or EU guidance |
Worked Example: The Same Two People, Five Equations
These use the same people as the calculators on this site: a 28-year-old man, 75 kg (165 lb), 178 cm (5 ft 10 in) and a 30-year-old woman, 65 kg (143 lb), 165 cm (5 ft 5 in), both moderately active (× 1.55). The lean-mass equations assume 15% body fat for him and 25% for her. Each BMR is rounded before multiplying, as the homepage, calorie and BMR calculators do. The Oxford equations are left out because this site does not reproduce their coefficients.
| Equation | Man: BMR | Man: TDEE | Woman: BMR | Woman: TDEE |
|---|---|---|---|---|
| Mifflin-St Jeor | 1,728 | 2,678 | 1,370 | 2,124 |
| Harris-Benedict (revised) | 1,788 | 2,771 | 1,430 | 2,217 |
| Schofield | 1,822 | 2,824 | 1,374 | 2,130 |
| Katch-McArdle | 1,747 | 2,708 | 1,423 | 2,206 |
| Cunningham | 1,903 | 2,950 | 1,573 | 2,438 |
How the man's figures are worked out: Mifflin-St Jeor is 750 + 1,112.5 − 140 + 5 = 1,727.5, rounded to 1,728. His lean mass is 75 × 0.85 = 63.75 kg, so Katch-McArdle is 370 + 21.6 × 63.75 = 1,747 and Cunningham is 500 + 22 × 63.75 = 1,902.5, rounded to 1,903. Schofield uses his 18–30 band: 15.057 × 75 + 692.2 = 1,821.5, rounded to 1,822. The woman is 30, so her Schofield figure uses the 30–60 band, and her lean mass is 65 × 0.75 = 48.75 kg.
Leaving out Cunningham, the other four land within about 95 kcal of each other at rest for the man and 60 kcal for the woman. Cunningham sits well above the rest for both, which is why it suits people who really do carry more lean mass and train often.
Activity Multipliers Matter More Than the Formula
Move the same man up one activity level, from × 1.55 to × 1.725, and his Mifflin-St Jeor TDEE rises from 2,678 to 2,981 kcal, a jump of about 300 kcal. That is more than the gap between any two of the first four equations above. Picking an honest activity level is the single most useful thing you can do for accuracy.
| Activity level | Multiplier | Typical week |
|---|---|---|
| Sedentary | × 1.2 | Desk job, little or no exercise |
| Lightly active | × 1.375 | Light exercise 1–3 days a week |
| Moderately active | × 1.55 | Moderate exercise 3–5 days a week |
| Very active | × 1.725 | Hard exercise 6–7 days a week |
| Extremely active | × 1.9 | Physical job or training twice a day |
Gym sessions add less than most people expect. On the workout calorie calculator, general weight training is 3.5 MET, so 45 minutes at 75 kg burns about 197 kcal. Four sessions a week average roughly 113 kcal a day, which does not turn a desk worker into "very active". Daily walking and standing often matter more, as the NEAT vs cardio guide explains.
These calculator multipliers are a rule of thumb, not the scale researchers use. The FAO/WHO/UNU expert report defines physical activity level (PAL) as total energy expenditure divided by BMR. It classes a sedentary or light lifestyle as PAL 1.40–1.69, an active one as 1.70–1.99 and a vigorous one as 2.00–2.40, and notes that extremely low energy expenditure allows survival but is not compatible with long-term health (FAO/WHO/UNU, 2004). The calculator "sedentary" factor of 1.2 sits below that whole range. One practical reading: for most desk workers, a sedentary result is a conservative starting point rather than a precise one.
Why Your Real TDEE Can Differ From Any Formula
Even a perfect equation cannot know everything about you. In the Scottish study of 150 adults, fat-free mass explained 63% of the differences in BMR between people, fat mass 6% and age 2%, and 26% remained unexplained (Johnstone et al., 2005). Two people with the same height, weight, age and sex can therefore burn noticeably different amounts at rest.
- Body composition: More lean mass means a higher resting burn than a weight-only equation predicts.
- Activity guess: The multiplier is a category, and real weeks vary.
- Dieting: After weight loss, energy expenditure can fall a little more than body size alone predicts. The reverse dieting guide covers this.
- Who was studied: The 2005 review found older adults and US ethnic minorities underrepresented in the research behind these equations.
If your TDEE seems too low or too high, check the activity level first, then calibrate against your own weight trend.
The 21-Day Calibration Check
No formula accounts for everything about one person. Treat your calculated TDEE as a starting point and check it against real data:
- Days 1–7 (baseline): Eat at your calculated TDEE every day. Weigh yourself each morning after waking.
- Days 8–14 (trend): Keep eating the same amount. Compare the 7-day median weight of week 1 with week 2.
- Days 15–21 (adjust): If weight is stable, within about 0.14 kg (0.3 lb), your estimate is close. If you are losing weight without meaning to, add (kilograms lost per week × 7,700) ÷ 7 calories a day. If you are gaining, subtract that amount. The calorie calculator uses the same 7,700 kcal per kilogram.
Frequently Asked Questions
What is the most accurate TDEE formula?
For most adults, Mifflin-St Jeor. A 2005 systematic review found it predicted resting metabolic rate within 10% of measured values in more people than the other common equations, with the narrowest error range. If you train often and have a measured body-fat figure, Cunningham did well in a 2014 study of recreational athletes. Whichever you use, the activity multiplier usually adds more error than the equation.
What is the TDEE formula for women?
Mifflin-St Jeor for women is (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161, then multiplied by an activity factor. A 30-year-old woman who is 65 kg and 165 cm has a BMR of about 1,370 kcal, and a moderately active TDEE of about 2,124 kcal (1,370 × 1.55).
How do I calculate TDEE in pounds and inches?
Use the imperial form of Mifflin-St Jeor: (4.536 × weight in lb) + (15.875 × height in inches) − (5 × age), then add 5 for men or subtract 161 for women. Multiply that BMR by your activity factor. A 165 lb, 5 ft 10 in, 28-year-old man gets about 1,728 kcal at rest and 2,678 kcal at moderate activity.
Is Katch-McArdle more accurate than Mifflin-St Jeor?
Only when your body-fat percentage is accurate. Katch-McArdle uses lean body mass, which explains more of the difference in resting burn between people than weight does, but a body-fat estimate that is off by a few points moves the result. Without a reliable figure, Mifflin-St Jeor is the safer choice.
Is the Harris-Benedict formula still reliable?
It is usable but tends to read high. In the 1990 Mifflin study the original 1919 equations overestimated measured resting energy expenditure by about 5%, and the 1984 revision has a reported precision of about ±14%. Most dietitians now start with Mifflin-St Jeor or, in the UK and EU, the Oxford (Henry) equations.
Why is my TDEE lower or higher than the calculator says?
Formulas estimate averages. In one study, about a quarter of the differences in BMR between people could not be explained by body composition or age. The more common cause is the activity level: one step on the multiplier scale changes TDEE by about 300 kcal for an average man. Track your intake and weight for two to three weeks and adjust from there.
Sources
- Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition. 1990;51(2):241–247.
- Frankenfield D, Roth-Yousey L, Compher C. Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review. Journal of the American Dietetic Association. 2005;105(5):775–789.
- Roza AM, Shizgal HM. The Harris Benedict equation reevaluated: resting energy requirements and the body cell mass. American Journal of Clinical Nutrition. 1984;40(1):168–182.
- Cunningham JJ. A reanalysis of the factors influencing basal metabolic rate in normal adults. American Journal of Clinical Nutrition. 1980;33(11):2372–2374.
- Cunningham JJ. Body composition as a determinant of energy expenditure: a synthetic review and a proposed general prediction equation. American Journal of Clinical Nutrition. 1991;54(6):963–969.
- ten Haaf T, Weijs PJM. Resting energy expenditure prediction in recreational athletes of 18–35 years: confirmation of Cunningham equation and an improved weight-based alternative. PLoS One. 2014;9(9):e108460.
- Johnstone AM, Murison SD, Duncan JS, Rance KA, Speakman JR. Factors influencing variation in basal metabolic rate include fat-free mass, fat mass, age, and circulating thyroxine but not sex, circulating leptin, or triiodothyronine. American Journal of Clinical Nutrition. 2005;82(5):941–948.
- Henry CJK. Basal metabolic rate studies in humans: measurement and development of new equations. Public Health Nutrition. 2005;8(7A):1133–1152.
- Schofield WN. Predicting basal metabolic rate, new standards and review of previous work. Human Nutrition: Clinical Nutrition. 1985;39(Suppl 1):5–41.
- FAO/WHO/UNU. Human Energy Requirements: Report of a Joint FAO/WHO/UNU Expert Consultation. FAO Food and Nutrition Technical Report Series 1. Rome: FAO; 2004.
- Scientific Advisory Committee on Nutrition. Dietary Reference Values for Energy. London: The Stationery Office; 2011.
- McArdle WD, Katch FI, Katch VL. Exercise Physiology: Nutrition, Energy, and Human Performance. Lippincott Williams & Wilkins.
Related Guides
- NEAT vs cardio: how everyday movement sets most of the activity multiplier.
- Reverse dieting: how to return to maintenance calories after a diet.
- Methodology: the equations and sources behind every calculator on this site.
Calculate Your TDEE Now
Enter your age, weight, height and activity level to get an estimate of your BMR, TDEE and calorie target.