Macro (IIFYM) Calculator & Splitter
Calculate precise macronutrient ratios (Protein, Fats, Carbs) based on TDEE. Supports Keto, Low-Carb, and Bodybuilding splits.
About
Energy balance dictates weight change, but macronutrient composition dictates body composition. This tool implements the Mifflin-St Jeor equation, widely considered the most accurate metabolic formula for non-obese individuals, to determine Total Daily Energy Expenditure (TDEE). It then applies specific split protocols to partition calories into Protein, Fats, and Carbohydrates.
Precision is vital for performance. Undereating protein during a caloric deficit (Cut) leads to muscle atrophy, while insufficient fats can crash hormonal production. This calculator allows you to toggle between standard splits (e.g., 40/40/20) and specialized protocols like Ketogenic or High-Carb Performance.
Formulas
We calculate Basal Metabolic Rate (BMR) first. The male adjustment is + 5, while female is − 161.
Total expenditure (TDEE) multiplies BMR by an activity factor (α). Macros are then derived using caloric densities: Protein (4 kcal/g), Carbs (4 kcal/g), Fat (9 kcal/g).
Reference Data
| Split Type | Protein (%) | Fats (%) | Carbs (%) | Best For |
|---|---|---|---|---|
| Balanced | 30% | 35% | 35% | General Health |
| Low Carb | 40% | 40% | 20% | Fat Loss / Satiety |
| Keto | 25% | 70% | 5% | Ketosis Induction |
| High Protein | 50% | 20% | 30% | Aggressive Cutting |
| Endurance | 20% | 20% | 60% | Marathon/Triathlon |