Macro Calculator

A macro calculator converts daily energy needs into a practical macronutrient plan. Age, sex, height, weight, and activity level compute Basal Metabolic Rate (BMR) and Total Daily Energy Expenditure (TDEE); a goal of maintain, lose, or gain then adjusts the calorie target, and a macro distribution preset or a custom split totaling 100% sets the protein, carb, and fat breakdown.

The path to a repeatable result:

• Two BMR formulas are available: Mifflin-St Jeor, from height, weight, age, and sex, or Katch-McArdle, from estimated body fat to compute lean body mass.
• Macro presets, Balanced, Low Fat, Low Carb, and High Protein, are available alongside a Custom split entered as protein, carb, and fat percentages summing to 100.
• Results display in Calories or Kilojoules.

The formulas, in plain text:

• Mifflin-St Jeor (male): BMR = 10·W + 6.25·H − 5·A + 5
• Mifflin-St Jeor (female): BMR = 10·W + 6.25·H − 5·A − 161
• Katch-McArdle: LBM = W × (1 − BF%); BMR = 370 + 21.6·LBM
• Activity factor (TDEE): Sedentary 1.20, Somewhat Active 1.375, Active 1.55, Very Active 1.725, Intense 1.90
• TDEE = BMR × activity factor
• Goal calories: Maintain = TDEE; Lose = TDEE − 500; Gain = TDEE + 500
• Macro grams: Protein g = (Calories × Protein%) ÷ 4; Carbs g = (Calories × Carbs%) ÷ 4; Fat g = (Calories × Fat%) ÷ 9
• Sugar limit ≈ 10% of calories: Max Sugar g = (Calories × 0.10) ÷ 4
• Saturated fat limit ≈ 10% of calories: Max Sat Fat g = (Calories × 0.10) ÷ 9
• kJ conversion: Kilojoules = Calories × 4.184
• Unit conversions: 1 in = 2.54 cm; 1 ft = 30.48 cm; 1 lb = 0.453592 kg

Macro targets apply across fitness, nutrition planning, and everyday health goals, translating a calorie target into clear grams for shopping, meal prepping, or food logging. The plan adapts as training volume, body composition, or objectives change.

• Weight maintenance: Energy intake aligned with TDEE holds weight steady during steady training phases; a Balanced preset supports overall performance and recovery.
• Fat loss phases: Calories reduced to TDEE − 500, paired with a High Protein or Low Carb split, support satiety and lean mass retention during a deficit.
• Muscle gain periods: Calories increased to TDEE + 500, with a split such as High Protein and moderate carbohydrates, supports training volume during a gain phase.
• Endurance training: A higher carbohydrate split fuels longer sessions, with protein held sufficient for recovery.
• Low-fat emphasis: The Low Fat preset prioritizes carbohydrates and protein while keeping dietary fat within recommended ranges.
• Custom nutrition strategies: A custom macro ratio matches a coach's plan or a medical recommendation, with the three percentages totaling 100.
• Meal planning and grocery lists: Daily grams convert into per-meal targets for shopping and batch cooking.
• Progress check-ins: Targets recalculate after weight changes, new training blocks, or shifts in activity level.
• Education and comparisons: Mifflin-St Jeor and Katch-McArdle produce different BMR estimates from the same inputs, and activity factors change TDEE independently of the formula chosen.

This tool is intended for informational and educational purposes only. It does not provide medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider for any health-related concerns or decisions.