How Calorie Cal works

Transparent. Private. Based on the best available free equations.

The three equations we support

Mifflin-St Jeor (default & recommended)

Widely regarded as the most accurate BMR equation for the general population. Used as the foundation for most modern TDEE calculators.

Men:   BMR = 10W + 6.25H − 5A + 5
Women: BMR = 10W + 6.25H − 5A − 161

W = kg, H = cm, A = years.

Revised Harris-Benedict

The 1984 revision of the classic equation. Still popular in many tools.

Katch-McArdle

Uses lean body mass. Best when you have a reliable body fat measurement (DEXA, good calipers). Not ideal if guessing BF%.

BMR = 370 + 21.6 × (lean mass kg)

From BMR → TDEE → Goal

  1. 1. Calculate BMR (energy to exist at complete rest).
  2. 2. Multiply by activity factor (1.2–1.9) → TDEE = maintenance calories.
  3. 3. Apply goal adjustment (−500 / −250 / 0 / +300) for your target shown in big green.

1 lb fat ≈ 3500 calories. A 500 kcal daily deficit theoretically produces ~1 lb loss per week (real life varies).

Zigzag / Calorie Cycling

Alternating higher and lower calorie days gives flexibility for social meals and hard training days. Research has not shown that it prevents metabolic adaptation, so use it if it makes your plan easier to follow. Use the interactive Weekly Cycling Planner directly in the calculator (with presets and editable days).

Related guides

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Sources

Studies and guidelines this page is based on:

  1. 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. doi.org/10.1093/ajcn/51.2.241
  2. 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. doi.org/10.1093/ajcn/40.1.168
  3. Frankenfield D, Roth-Yousey L, Compher C. Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review. J Am Diet Assoc. 2005;105(5):775-789. doi.org/10.1016/j.jada.2005.02.005
  4. Hall KD, Sacks G, Chandramohan D, Chow CC, Wang YC, Gortmaker SL, Swinburn BA. Quantification of the effect of energy imbalance on bodyweight. Lancet. 2011;378(9793):826-837. doi.org/10.1016/S0140-6736(11)60812-X
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