What Is the Schofield Equation?
The Schofield Equation is one of the most widely adopted mathematical models in global nutritional science for estimating Basal Metabolic Rate (BMR)—the minimum amount of daily energy (calories or megajoules) an individual expends at complete physical and thermal rest.
Published in 1985 by British researcher W. N. Schofield in the journal Human Nutrition: Clinical Nutrition, the equations were synthesized from an exhaustive statistical screening of over 114 metabolic studies spanning 7,173 individual basal metabolism measurements collected across the 20th century.
Shortly after publication, the Schofield equations were formally adopted by the Joint FAO/WHO/UNU Expert Consultation on Energy and Protein Requirements (WHO Technical Report Series 724) as the international standard for calculating human energy requirements across populations.
Schofield Formula Variants: Weight-Only vs. Weight + Height
In his original 1985 monograph, Schofield formulated two distinct families of regression equations categorized across six age categories for both males and females:
Weight-Only Regression Equations
These equations estimate BMR using body weight ($W$ in kg) alone. Because height added only marginal statistical variance in adult groups while complicating field measurements, the FAO/WHO/UNU selected the weight-only set for international dietary guidelines.
Weight + Height Regression Equations
These models incorporate both body weight ($W$ in kg) and body height ($H$ in cm). While height provided minor precision improvements in children and elderly populations, the dual-variable equation accounts for body surface stature in taller or shorter individuals.
Complete Schofield (1985) Equation Reference Table
Verified regression models adopted by FAO/WHO/UNU for basal metabolic rate prediction.
| Sex | Age Group | Formula (kcal/day) | SI Standard (MJ/day) | Standard Error |
|---|---|---|---|---|
| Men / Males | < 3 years | 59.512 × W - 30.4 | 0.249 × W - 0.127 | ±0.292 MJ (±70 kcal) |
| 3–10 years | 22.706 × W + 504.3 | 0.095 × W + 2.11 | ±0.28 MJ (±67 kcal) | |
| 10–18 years | 17.686 × W + 658.2 | 0.074 × W + 2.754 | ±0.441 MJ (±105 kcal) | |
| 18–30 years | 15.057 × W + 692.2 | 0.063 × W + 2.896 | ±0.641 MJ (±153 kcal) | |
| 30–60 years | 11.472 × W + 873.1 | 0.048 × W + 3.653 | ±0.7 MJ (±167 kcal) | |
| > 60 years | 11.711 × W + 587.7 | 0.049 × W + 2.459 | ±0.65 MJ (±155 kcal) | |
| Women / Females | < 3 years | 58.317 × W - 31.1 | 0.244 × W - 0.13 | ±0.252 MJ (±60 kcal) |
| 3–10 years | 20.315 × W + 485.9 | 0.085 × W + 2.033 | ±0.25 MJ (±60 kcal) | |
| 10–18 years | 13.384 × W + 692.6 | 0.056 × W + 2.898 | ±0.465 MJ (±111 kcal) | |
| 18–30 years | 14.818 × W + 486.6 | 0.062 × W + 2.036 | ±0.497 MJ (±119 kcal) | |
| 30–60 years | 8.126 × W + 845.6 | 0.034 × W + 3.538 | ±0.465 MJ (±111 kcal) | |
| > 60 years | 9.082 × W + 658.5 | 0.038 × W + 2.755 | ±0.45 MJ (±107 kcal) |
Notation: W = body weight in kilograms (kg); H = body height in centimetres (cm).
Source: Schofield, W.N. (1985), Human Nutrition: Clinical Nutrition 39C (Suppl 1): 5–41 & WHO Technical Report Series 724.
BMR vs. RMR vs. TDEE: Understanding the Core Differences
In fitness and dietetics, metabolic terms are frequently conflated. However, each term represents a distinct physiological state:
| Metabolic Metric | Full Definition | Measurement Conditions | Relative Calorie Scale |
|---|---|---|---|
| BMR (Schofield Output) | Basal Metabolic Rate | Strict 12h fast, post-sleep awakening, thermo-neutral room, zero movement. | Baseline (100%) |
| RMR / REE | Resting Metabolic Rate | Resting seated/supine, 4–5h post-meal, relaxed clinic conditions. | ~103–110% of BMR |
| TDEE | Total Daily Energy Expenditure | Full 24h expenditure: BMR + Physical Activity (PAL) + TEF (Digestion) + NEAT. | ~130–220% of BMR |
⚠️ Critical Takeaway:
The Schofield equation calculates your BMR baseline, which accounts for roughly 60% to 75% of your total daily calorie burn. To maintain or change your body weight, you must account for your physical activity multiplier (PAL) using a full Total Daily Energy Expenditure (TDEE) calculator.
Scientific Strengths & Known Limitations of the Schofield Equation
✓ Major Scientific Strengths
- Broad Demographic Span: Validated equations spanning from infancy (under 3) through geriatric populations (60+).
- Zero Equipment Barrier: Reliable weight-only estimation without requiring expensive hydrostatic weighing or DEXA scans.
- International Standardization: Used by the United Nations and national health ministries for macroeconomic food aid and population nutrition policies.
⚠️ Documented Limitations
- Cohort Selection Bias: The 1985 historical database included a disproportionate number of Italian military recruits and North European subjects.
- Potential Overestimation: Studies in tropical and sedentary adult populations indicate Schofield can overestimate true BMR by 5% to 11%.
- No Body Composition Factor: Does not differentiate between high muscularity and adipose tissue (unlike the Katch-McArdle formula).
Frequently Asked Questions About the Schofield Equation
What is the difference between Schofield and Mifflin-St Jeor?▼
Schofield was developed in 1985 and is heavily utilized in global public health and international policy. Mifflin-St Jeor was published in 1990 using a contemporary cohort and is widely referenced for healthy adults due to a lower tendency to overestimate BMR.
Why does the Schofield weight-only equation not ask for height?▼
In Schofield's statistical regressions, adding height to body weight yielded only negligible improvements in predictive variance for most adult age categories. To maintain simplicity for field and public health applications, the FAO/WHO selected the weight-only model as the primary global standard.
Can I use the Schofield BMR result for children?▼
Yes, Schofield includes specific regression models for ages 0–3, 3–10, and 10–18. However, because growing children expend substantial energy synthesizing new tissues (growth energy costs), BMR must never be used in isolation to restrict caloric intake for a growing youth. Always consult a qualified professional or guardian.
How do I convert Schofield MJ/day to kcal/day?▼
1 Megajoule (MJ) is equal to approximately 238.846 kilocalories (kcal). To convert a Megajoule result to kcal, multiply by 238.85 (or divide by 0.004184).
Peer-Reviewed References & Authoritative Sources
- Schofield, W. N. (1985). Predicting basal metabolic rate, new standards and review of previous work. Human Nutrition. Clinical Nutrition, 39 Suppl 1, 5–41. PMID: 4044297.
- FAO/WHO/UNU Expert Consultation (1985). Energy and protein requirements. World Health Organization Technical Report Series 724. Geneva: WHO.
- Food and Agriculture Organization (2004). Human energy requirements. Report of a Joint FAO/WHO/UNU Expert Consultation. FAO Food and Nutrition Technical Report Series 1. Rome: FAO.
- Mifflin, M. D., St Jeor, S. T., Hill, L. A., Scott, B. J., Daugherty, S. A., & Koh, Y. O. (1990). A new predictive equation for resting energy expenditure in healthy individuals. The American Journal of Clinical Nutrition, 51(2), 241–247. PMID: 2305711.
- Roza, A. M., & Shizgal, H. M. (1984). The Harris Benedict equation reevaluated: resting energy requirements and the body cell mass. The American Journal of Clinical Nutrition, 40(1), 168–182. PMID: 6741850.