What Is the Owen Equation?

Owen and colleagues published sex-specific resting metabolic rate (RMR) prediction equations in the American Journal of Clinical Nutrition in 1986 (women) and 1987 (men). Their key finding: in their samples, body weight alone predicted RMR about as well as more complex models — making Owen one of the simplest validated weight-based equations used in nutrition and exercise science references.

BMR vs RMR vs REE vs TDEE

Metric

BMR

What it measures

Strict basal conditions (fasting, rest, thermoneutral)

Best use

Gold-standard terminology in physiology

Metric

RMR / REE

What it measures

Resting energy under less strict lab protocols

Best use

Owen primary source term — what the papers measured

Metric

TDEE

What it measures

Total daily energy (RMR × activity factor)

Best use

Maintenance and goal calorie planning

This calculator shows one resting-energy estimate labeled BMR / RMR (Owen) — not two separate numbers. Predictive equations derived from RMR data are commonly applied as practical BMR estimates for meal planning.

Official Owen Equations (Weight-Only)

Owen (1987) — men

BMR/RMR (kcal/day) = 879 + 10.2 × weight (kg)

Source: Owen et al. (1987) — men 18–82 y.
kg
Body weight in kilograms (only required input besides sex)
879 / 795
Sex-specific intercept (kcal/day)
10.2 / 7.18
Sex-specific weight coefficient (kcal per kg)

Owen (1986) — non-athlete women

BMR/RMR (kcal/day) = 795 + 7.18 × weight (kg)

Source: Owen et al. (1986) — non-athlete women 18–65 y.
(Owen also published a separate athlete equation — not used as the default here.)
kg
Body weight in kilograms (only required input besides sex)
879 / 795
Sex-specific intercept (kcal/day)
10.2 / 7.18
Sex-specific weight coefficient (kcal per kg)

Sex

Male

Population

General (1987)

RMR (kcal/day)

879 + 10.2×W

Sex

Female

Population

Non-athlete (1986)

RMR (kcal/day)

795 + 7.18×W

Sex

Female

Population

Athlete (1986, reference only)

RMR (kcal/day)

50.4 + 21.1×W

Worked Examples

Adult male: 80 kg

Owen (1987) men.

  1. RMR = 879 + (10.2 × 80)
  2. RMR = 879 + 816 = 1,695 kcal/day

Result: Estimated BMR/RMR ≈ 1,695 kcal/day

Adult female: 65 kg (non-athlete)

Owen (1986) non-athlete women.

  1. RMR = 795 + (7.18 × 65)
  2. RMR = 795 + 466.7 ≈ 1,262 kcal/day

Result: Estimated BMR/RMR ≈ 1,262 kcal/day

Higher weight male: 95 kg

Weight-only prediction.

  1. RMR = 879 + (10.2 × 95)
  2. RMR = 879 + 969 = 1,848 kcal/day

Result: Estimated BMR/RMR ≈ 1,848 kcal/day

Older adult female: 72 kg

Owen does not include age — same formula at any adult age.

  1. RMR = 795 + (7.18 × 72)
  2. RMR = 795 + 517 ≈ 1,312 kcal/day

Result: Estimated BMR/RMR ≈ 1,312 kcal/day — compare with Mifflin if height known

Why Body Weight Alone?

Owen's regressions in both the 1986 (women) and 1987 (men) papers found body weight highly related to RMR, with stepwise addition of other variables not improving predictions in their samples. In men, the age effect on RMR was described as trivial. That makes Owen fast and useful when height is unknown — but it also means the equation cannot distinguish high muscle mass from high fat mass at the same weight. Individual metabolic variability remains substantial.

How This Calculator Works

Step

1. Demographics

What you enter

Sex, weight

Result

Selected Owen equation (1986/1987)

Step

2. BMR/RMR

What you enter

Weight-only Owen formula

Result

Resting kcal/day + ±10% range

Step

3. TDEE

What you enter

Activity multiplier (1.2–1.9)

Result

Maintenance at each activity level

Step

4. Goals

What you enter

Deficit or surplus selection

Result

Target calories for your goal

Owen vs Mifflin-St Jeor

Mifflin-St Jeor (1990)

Male:
BMR = (10 × kg) + (6.25 × cm)
    − (5 × age) + 5

Female:
BMR = (10 × kg) + (6.25 × cm)
    − (5 × age) − 161
kg
Body weight in kilograms
cm
Height in centimeters
age
Age in years

Mifflin requires weight, height, age, and sex — and is often preferred for healthy adults when height is known (Frankenfield 2005). Owen needs only weight and sex, making it useful for quick estimates or when height is unavailable. Compare both when optional demographics are entered — neither replaces individual calibration.

Owen vs Harris-Benedict

Harris-Benedict (revised 1984)

Male:
BMR = 88.362 + (13.397 × kg)
    + (4.799 × cm) − (5.677 × age)

Female:
BMR = 447.593 + (9.247 × kg)
    + (3.098 × cm) − (4.330 × age)
kg
Body weight in kilograms
cm
Height in centimeters
age
Age in years

Harris-Benedict uses four inputs (weight, height, age, sex) without Owen's weight-only simplicity. For adults, equations often land in a similar ballpark, but divergence increases at extremes of height or age. Owen was validated in adults roughly 18–65/82 years — not for pediatrics.

Owen vs Katch-McArdle & Cunningham

Katch-McArdle

Lean mass (kg) = weight (kg)
    × (1 − body fat % / 100)

BMR = 370 + (21.6 × lean mass kg)
kg
Body weight in kilograms
BF%
Body fat percentage (required)

Cunningham (1980)

RMR = 500 + (22 × lean mass kg)

Lean mass can be entered directly, or:
  lean mass = weight (kg) × (1 − body fat % / 100)
kg
Lean body mass in kilograms

Lean-mass equations account for body composition — often preferable for athletes when body fat % or lean mass is known. O'Neill et al. (2023) found Owen differed significantly from measured RMR in pooled athlete data and listed it among equations to avoid for athletic populations. Owen remains a reasonable starting point for general adults when composition data is unavailable.

TDEE estimate error comes from two stacked layers — and the second is usually bigger in practice.

Layer 1: BMR formula error

Mifflin-St Jeor predicts resting metabolic rate within ~10% for roughly 82% of non-obese adults and ~70% of obese adults (Frankenfield et al., 2005). That is ±150–200 kcal for many people.

Layer 2: Activity multiplier error

Picking one activity bucket too high adds ~200–400 kcal/day. Most people remember gym time but underestimate desk hours. Take our Activity Level Quiz if unsure.

Indirect calorimetry remains the gold standard for measured resting energy. Predictive equations — including Owen — are starting estimates with individual variation. See our methodology for activity multipliers and calibration guidance.

Who Should Use the Owen Equation?

General adults who want a quick weight-based RMR estimate, users without height data, and educators comparing predictive equations. For children and teens, use the Schofield Calculator (WHO age bands). For athletes with composition data, consider Katch-McArdle or Cunningham. This calculator is informational only — not clinical prescribing.

Common Mistakes

  • Expecting age to change Owen RMR — age is not in the Owen formula; use optional cross-checks if you want age-aware equations.
  • Confusing RMR with TDEE — multiply by activity before planning deficits or surpluses.
  • Using Owen for athletes without comparison — lean-mass equations may fit better when body composition is known.
  • Treating any equation as exact — validate with 2–3 weeks of weight trends at your chosen intake.

Myths vs Facts

Myth

Owen is always more accurate because it is simpler.

Evidence-based view

Simplicity does not guarantee accuracy. Frankenfield (2005) often favors Mifflin for general adults when height is known. Owen excels at weight-only workflows.

Myth

BMR and RMR are always different numbers here.

Evidence-based view

Owen outputs one predictive resting-energy estimate; terminology differs by measurement protocol, not by a second formula in this tool.

Myth

Owen works equally well for all athletes.

Evidence-based view

Owen (1986) published a separate athlete equation for women. O'Neill (2023) found Owen differed significantly from measured RMR in pooled athlete data — compare with lean-mass equations when composition is known.

Myth

Weight alone captures muscle vs fat.

Evidence-based view

At the same weight, lean and higher-fat individuals can differ in resting energy. Weight-only equations cannot separate composition.

Suggested next steps

RMR Calculator

RMR hub with fixed kcal goals

REE Calculator

All 7 equations + auto-select + TDEE

Mifflin-St Jeor Calculator

Adult-default BMR with height

Schofield Calculator

WHO age-band BMR for all ages

Katch-McArdle Calculator

Lean-mass BMR from body fat %

Macro Calculator

Turn goal calories into macros

Frequently Asked Questions

Common questions about the owen calculator.

Research & References

Each citation below supports a specific claim on this page. We explain relevance so you can verify the science yourself.

  1. National Academies of Sciences, Engineering, and Medicine — Factors Affecting Energy Expenditure and Requirements. Dietary Reference Intakes for Energy — NCBI Bookshelf, 2023.Defines TDEE components (REE, TEF, PAEE) and explains why population equations cannot capture individual metabolic variation.
  2. Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO — A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990;51(2):241-247, 1990.Primary source for the Mifflin-St Jeor BMR equation used as the default in this calculator.
  3. 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, 1984.Source for the revised Harris-Benedict coefficients — default equation on this calculator page.
  4. McArdle WD, Katch FI, Katch VL — Exercise Physiology: Energy, Nutrition, and Human Performance. Lippincott Williams & Wilkins, 7th edition, 2010.Textbook reference for the lean-body-mass-based Katch-McArdle resting energy estimate.
  5. Frankenfield D, Roth-Yousey L, Compher C — Comparison of Predictive Equations for Resting Metabolic Rate in Healthy Nonobese and Obese Adults. J Am Diet Assoc. 2005;105(5):775-789, 2005.Meta-analysis showing Mifflin-St Jeor within ~10% of measured RMR for ~82% of non-obese and ~70% of obese adults — supports honest accuracy framing.
  6. O'Neill JER, Corish CA, Horner K — Accuracy of Resting Metabolic Rate Prediction Equations in Athletes: A Systematic Review with Meta-analysis. Sports Med. 2023;53(12):2373-2398, 2023.Athlete systematic review and meta-analysis — several common equations including Mifflin-St Jeor and Owen differed significantly from measured RMR in pooled athlete data; lean-mass equations (e.g., Cunningham 1980) and Ten-Haaf performed differently by population, with no single best equation for all athletes.
  7. Owen OE, Kavle EC, Owen RS, Polansky M, Caprio S, Mozzoli MA, Kendrick ZV, Bushman MC, Boden G — A reappraisal of caloric requirements in healthy women. Am J Clin Nutr. 1986;44(1):1-19, 1986.Primary source for Owen female RMR equations — non-athlete (795 + 7.18 × weight kg) and athlete (50.4 + 21.1 × weight kg) variants.
  8. Owen OE, Holup JL, D'Alessio DA, Craig ES, Polansky M, Smalley KJ, Kavle EC, Bushman MC, Owen LR, Mozzoli MA, Kendrick ZV, Boden G — A reappraisal of the caloric requirements of men. Am J Clin Nutr. 1987;46(6):875-885, 1987.Primary source for Owen male RMR equation (879 + 10.2 × weight kg) in men 18–82 years; found weight alone predicted RMR with age effect trivial.