Sources & References

Last updated: July 2026

FitCalCalc is built on published, widely-used formulas. Below are the primary sources for each calculator. We aim for transparency: you should always know where a number comes from.

Basal Metabolic Rate (BMR) & TDEE

• 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.
• Harris, J. A., & Benedict, F. G. (1919). A biometric study of basal metabolism in man. Carnegie Institution of Washington, Publication No. 279.
• World Health Organization. (1985). Energy and protein requirements: report of a joint FAO/WHO/UNU expert consultation. WHO Technical Report Series 724.
• Schofield, W. N. (1985). Predicting basal metabolic rate, new standards and review of previous work. Human Nutrition: Clinical Nutrition, 39 Suppl 1, 5–41.
• Katch, F. I., & McArdle, W. D. (1993). Nutrition, Weight Control, and Exercise. Lea & Febiger.
• Cunningham, J. J. (1980). A reanalysis of the factors influencing basal metabolic rate in normal adults. The American Journal of Clinical Nutrition, 33(11), 2372–2374.

Body Mass Index (BMI)

• Centers for Disease Control and Prevention (CDC). About Adult BMI. U.S. Department of Health and Human Services.
• World Health Organization. Physical status: the use and interpretation of anthropometry. WHO Technical Report Series 854.

Body Fat %

• Department of the Navy. The Navy Body Fat Formula. U.S. Navy Physical Readiness Program.
• Jackson, A. S., & Pollock, M. L. (1978). Generalized equations for predicting body density of men. British Journal of Nutrition, 40(3), 497–504.
• Jackson, A. S., Pollock, M. L., & Ward, A. (1980). Generalized equations for predicting body density of women. Medicine and Science in Sports and Exercise, 12(3), 175–182.
• Siri, W. E. (1956). The gross composition of the body. Advances in Biological and Medical Physics, 4, 239–280.

One-Rep Max (1RM)

• Epley, B. (1985). Peak performance: the science of success. Lincoln, NE: Epley.
• Brzycki, M. (1993). Strength testing — predicting a one-rep max from reps-to-fatigue. Journal of Physical Education, Recreation & Dance, 64(1), 88–90.

Activity & MET Values

• Ainsworth, B. E., Haskell, W. L., Herrmann, S. D., Meckes, N., Bassett, D. R., Tudor-Locke, C., … Leon, A. S. (2011). 2011 Compendium of Physical Activities: a second update of codes and MET values. Medicine & Science in Sports & Exercise, 43(8), 1575–1581.

Reverse TDEE & Weight Change

• Hall, K. D., Heymsfield, S. B., Kemnitz, J. W., Klein, S., Schoeller, D. A., & Speakman, J. R. (2012). Energy balance and its components: implications for body weight regulation. American Journal of Clinical Nutrition, 95(4), 989–994.
• Wishnofsky, M. (1958). Rules concerning the metabolism of human energy. Merck's Bulletin, 6, 1–36. (Commonly cited 3,500 kcal ≈ 1 lb rule of thumb.)

Water Intake

• Institute of Medicine (US). (2004). Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate. National Academies Press.
• Armstrong, L. E., et al. (2012). American College of Sports Medicine position stand: nutrition and athletic performance. Medicine & Science in Sports & Exercise, 44(1), 148–157.

Disclaimer

These references are provided for transparency and education. They do not constitute medical advice. See our Disclaimer and Terms of Service.