Macro Calculator

What is a Macro Calculator?

A macro calculator determines your daily macronutrient needs—carbohydrates, proteins, and fats—based on personal factors like age, gender, height, weight, activity level, and goals (weight loss, maintenance, or muscle gain). Macros fuel your body: Carbs for energy (4 cal/g), proteins for repair/growth (4 cal/g), fats for hormones/absorption (9 cal/g). In 2025, with 42% U.S. adult obesity (CDC), balanced macros support sustainable health—e.g., 45-65% carbs, 10-35% protein, 20-35% fat (AMDR guidelines).

This tool uses Mifflin-St Jeor for BMR, activity multipliers for TDEE, then goal-based ratios to allocate calories. It's a starting point—track via apps like MyFitnessPal; adjust based on progress (weigh weekly). Not for medical use; consult a dietitian for conditions like diabetes.

How the Calculator Works

  1. BMR: Resting calories via Mifflin-St Jeor (age/gender/height/weight).
  2. TDEE: BMR × activity factor.
  3. Goal Adjustment: Loss (-500 cal), Maintenance (TDEE), Gain (+500 cal).
  4. Macros: Goal-specific % split → grams (e.g., Loss: 40% carbs, 30% protein, 30% fat).

Sample: 30F, 5'4", 150 lbs, lightly active, loss goal. BMR: 1,346. TDEE: 1,851. Adjusted: 1,351 cal. Macros: 135g carbs, 101g protein, 45g fat.

Activity Levels & Goal Ratios

  • Sedentary: ×1.2 (desk job).
  • Lightly Active: ×1.375 (1-3x exercise/week).
  • Moderately Active: ×1.55 (3-5x).
  • Very Active: ×1.725 (6-7x).
  • Super Active: ×1.9 (intense + physical job).

Ratios:

  • Loss: 40% carbs, 30% protein, 30% fat (muscle-sparing).
  • Maintenance: 50% carbs, 25% protein, 25% fat (balanced).
  • Gain: 55% carbs, 25% protein, 20% fat (energy-focused).

Tips for Macro Success

  • Track & Adjust: Log meals; tweak if no progress (e.g., +100g protein for gains).
  • Food Sources: Carbs (oats, veggies); Protein (chicken, tofu); Fats (avocado, nuts).
  • Meal Prep: Divide into 3-5 meals; use 80/20 rule (80% whole foods).
  • Hydration: 0.5-1 oz/lb body weight; boosts metabolism 3%.
  • Common Pitfall: Over-restrict fats (<20%) harms hormones—aim balanced.

Frequently Asked Questions

Why gender/age?

  • Hormones/metabolism differ; women often lower BMR post-30.

Protein needs?

  • 1.6-2.2g/kg for active; calculator auto-scales.

Vegan options?

  • Yes—focus plant proteins (lentils, quinoa); supplement B12 if needed.

Recalculate when?

  • Every 5-10 lbs change or monthly.

Disclaimers

Estimates only—not advice. Varies by genetics/meds; minimums: 1,200 cal women/1,500 men. Risks: Obsessive tracking may trigger disorders. Consult pros for health issues. AMDR/CDC data (2025). No liability.

Balance your plate—calculate macros.

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