How to Use IIFYM Calculator
- Enter sex, age, weight, and height so the calculator can estimate BMR.
- Select an activity level that reflects your usual training and daily movement.
- Choose fat loss, maintenance, or muscle gain. The calculator adjusts calories before splitting macros.
- Use the protein, carbohydrate, and fat grams as daily targets for food logging or meal prep.
TDEE = BMR x activity factor
Goal calories = TDEE + goal adjustment
Protein (g) = protein calories / 4
Carbohydrates (g) = carbohydrate calories / 4
Fat (g) = fat calories / 9
- This tool uses a balanced IIFYM split: about 30% protein, 40% carbohydrates, and 30% fat.
- Protein and carbohydrates use 4 kcal per gram; fat uses 9 kcal per gram.
Use Cases for IIFYM Calculator
- Flexible dieting where food choices vary but daily macros still need structure.
- Meal prep planning for fat loss, maintenance, or lean mass gain.
- Checking whether a meal plan is too low in protein or too high in fat for the selected target.