What we found
Formula choice changed the estimated resting requirement by 81.6 kcal/day on average in this grid. The largest gap was 258.3 kcal/day. These are differences between equations, not errors measured against indirect calorimetry.
The largest disagreements appeared in heavier, younger male profiles. That pattern follows from the different weight, height, and age coefficients in each equation; it does not establish which estimate is correct for an individual.
If the same activity multiplier were applied to every estimate, the maintenance-calorie gap would grow proportionally. At a multiplier of 1.55, an 100 kcal resting-energy gap becomes approximately 155 kcal/day. Activity multipliers introduce another independent source of uncertainty.
Largest differences in the grid
| Profile | Mifflin | Revised H–B | Original H–B | Spread |
|---|---|---|---|---|
| Male, 20 y, 160 cm, 115 kg | 2055 | 2283.3 | 2313.3 | 258.3 kcal |
| Male, 20 y, 175 cm, 115 kg | 2148.8 | 2355.3 | 2388.4 | 239.6 kcal |
| Male, 40 y, 160 cm, 115 kg | 1955 | 2169.8 | 2178.2 | 223.2 kcal |
| Male, 20 y, 190 cm, 115 kg | 2242.5 | 2427.3 | 2463.4 | 220.9 kcal |
| Male, 40 y, 175 cm, 115 kg | 2048.8 | 2241.8 | 2253.3 | 204.5 kcal |
| Male, 60 y, 160 cm, 115 kg | 1855 | 2056.2 | 2043.1 | 201.2 kcal |
| Male, 40 y, 190 cm, 115 kg | 2142.5 | 2313.7 | 2328.3 | 185.8 kcal |
| Male, 20 y, 160 cm, 95 kg | 1855 | 2015.4 | 2038.3 | 183.3 kcal |
Method
We generated a complete grid from two equation sex constants, ages 20/40/60 years, heights 160/175/190 cm, and weights 55/75/95/115 kg. That produced 72 profiles. No personal records, patient data, or tracking data were used.
For each profile, we calculated predicted kcal/day using all three equations. “Spread” is the highest prediction minus the lowest. Values were calculated at full precision and rounded to one decimal place for publication. The implementation that generates this page also generates the CSV, preventing the displayed analysis and download from drifting apart.
Mifflin–St Jeor
Published 1990
Male constant
10W + 6.25H − 5A + 5Female constant
10W + 6.25H − 5A − 161Revised Harris–Benedict
Published 1984
Male constant
88.362 + 13.397W + 4.799H − 5.677AFemale constant
447.593 + 9.247W + 3.098H − 4.330AOriginal Harris–Benedict
Published 1918/1919
Male constant
66.473 + 13.752W + 5.003H − 6.755AFemale constant
655.096 + 9.563W + 1.850H − 4.676AW = weight in kg, H = height in cm, A = age in years.
Limitations
- This is a formula comparison using synthetic profiles, not a clinical validation study.
- It does not compare predictions with measured resting energy expenditure.
- The grid is deliberately regular and is not representative of any national population.
- The equations use sex-specific constants and do not model body composition, pregnancy, illness, medication, or athletic status.
- Individual energy needs can differ materially from every estimate shown here.
Primary sources
- Mifflin MD et al. A new predictive equation for resting energy expenditure in healthy individuals.PubMed 2305711.
- Roza AM, Shizgal HM. The Harris Benedict equation reevaluated: resting energy requirements and the body cell mass.PubMed 6741850.
- Harris JA, Benedict FG. A biometric study of human basal metabolism.PubMed 16576330.