REFERENCE_MANUAL // FORMULAS & DEFINITIONS
◉ MODULE_01
Your weight minus body fat. It includes muscles, bones, organs, and water. LBM is the base for all macro targets — not total body weight — because fat tissue has minimal metabolic activity and doesn't need protein or carbs to be sustained.
BOER (DEFAULT)
Male: 0.407 × W + 0.267 × H − 19.2
Female: 0.252 × W + 0.473 × H − 48.3
W = weight (kg), H = height (cm)
JAMES
Male: 1.1 × W − 128 × (W/H)²
Female: 1.07 × W − 148 × (W/H)²
Can underestimate LBM in obese individuals.
HUME
Male: 0.3281 × W + 0.33929 × H − 29.5336
Female: 0.29569 × W + 0.41813 × H − 43.2933
MANUAL
Enter your LBM directly if you have a body composition measurement (DEXA, BodPod, etc.).
◉ MODULE_02
Calories your body burns at complete rest — just to keep organs functioning. It's the floor of your energy needs. Everything on top of it comes from physical activity.
MIFFLIN-ST JEOR
Male: 10W + 6.25H − 5A + 5
Female: 10W + 6.25H − 5A − 161
W = weight (kg), H = height (cm), A = age (yrs). Best accuracy for the general population.
REVISED HARRIS-BENEDICT
Male: 13.397W + 4.799H − 5.677A + 88.362
Female: 9.247W + 3.098H − 4.33A + 447.593
Classic formula revised by Roza & Shizgal (1984). Slightly higher estimates than Mifflin.
KATCH-MCARDLE (DEFAULT)
370 + 21.6 × LBM (kg)
Uses LBM instead of total weight — more accurate when body composition is known. Gender-neutral.
◉ MODULE_03
Your actual daily calorie burn. Calculated as BMR multiplied by an activity factor that accounts for exercise and lifestyle.
TDEE = BMR × activity_multiplier
◉ MODULE_04
MAINTAIN
Calories = TDEE
Sustain current weight. Balanced macro split to support activity and body composition.
SURPLUS
Calories = TDEE + 300 kcal
Moderate caloric surplus to support muscle growth. Higher carbs fuel training; fat set to 25% of total calories.
DEFINITION
Calories = TDEE − 300 kcal
Moderate deficit for fat loss. Protein is raised to preserve muscle mass. Carbs fill the remaining calories.
◉ MODULE_05
Grams of each macro are set per kg of LBM (not total weight). Carbs always fill the remaining calories after protein and fat are accounted for.
PROTEIN TARGETS (per kg LBM)
FAT TARGETS
CARBS
Remainder = (total_kcal − protein_kcal − fat_kcal) / 4
◉ FAQ
Lean Body Mass is your total weight minus body fat — it includes muscle, bone, organs, and water. MacroCalc uses LBM as the base for all macro targets because fat tissue has minimal metabolic activity and does not need protein or carbs to be sustained. This gives more accurate targets than using total body weight.
BMR is the number of calories your body burns at complete rest — the minimum energy needed to keep organs functioning. MacroCalc supports three equations: Mifflin-St Jeor (best for general population), Revised Harris-Benedict, and Katch-McArdle (most accurate when body composition is known, uses LBM).
TDEE = BMR × an activity multiplier. Sedentary (×1.2), Lightly active (×1.375), Moderately active (×1.55), Very active (×1.725), Extremely active (×1.9). This gives your actual daily calorie burn including exercise and lifestyle activity.
Protein and fat are set in grams per kg of LBM based on your goal. Carbs fill the remaining calories. Maintenance: 1.8 g protein/kg LBM, 1.0 g fat/kg LBM. Surplus: 2.0 g protein, fat at 25% of total calories. Definition: 2.5 g protein, 0.9 g fat/kg LBM.
Maintain keeps calories at TDEE for weight stability. Surplus adds +300 kcal to TDEE to support muscle growth. Definition subtracts −300 kcal from TDEE for moderate fat loss (estimated ~0.5 kg/week per 500 kcal deficit).