IIFYM Calculator
IIFYM Calculator — If It Fits Your Macros
Your Stats
Your Daily Macros
Based on your results — what to do next:
Check your BMI & healthy weight range
At 185 lbs, see where you fall on the BMI scale and what your ideal body weight is for your height.
Budget for your nutrition
Hitting 179g protein daily on whole foods adds up. Plan your monthly grocery budget alongside your macro goals.
Apply the same discipline to money
IIFYM's "track everything" approach works for finances too. See how optimizing your spending rate accelerates financial independence.
IIFYM (If It Fits Your Macros) calculates your exact daily targets for protein, carbs, and fat based on your body stats, activity level, and goal — cut, maintain, or bulk. Enter your numbers to get a personalized macro split, per-meal breakdown, and estimated weekly weight change.
How IIFYM Macros Are Calculated
IIFYM starts with your TDEE (Total Daily Energy Expenditure) — the calories your body burns daily at your activity level. Your goal determines the calorie adjustment (deficit for cutting, surplus for bulking). Those calories are then split into grams of protein, carbs, and fat based on your chosen percentage split.
| Variable | Definition |
|---|---|
| BMR | Basal Metabolic Rate — calories burned completely at rest (Mifflin-St Jeor, Harris-Benedict, or Katch-McArdle) |
| TDEE | Total Daily Energy Expenditure — BMR × activity multiplier (1.2–1.9) |
| ÷ 4 | Protein and carbs each provide 4 calories per gram |
| ÷ 9 | Fat provides 9 calories per gram |
| Goal Modifier | Cut: −15–25% · Maintain: 0% · Lean Bulk: +10% · Bulk: +20% |
Worked example: Male, 28, 5'10", 185 lbs, moderate activity (TDEE multiplier 1.55), goal: cut. BMR = 1,859 cal. TDEE = 1,859 × 1.55 = 2,881 cal. Cut target (−15%) = 2,449 cal/day. At 30/25/45 split: Protein = (2,449 × 0.30) ÷ 4 = 184g. Fat = (2,449 × 0.25) ÷ 9 = 68g. Carbs = (2,449 × 0.45) ÷ 4 = 275g.
⚡ IIFYM Pro Tip
Hit Protein First, Fill the Rest: The single most important macro is protein. It preserves muscle during a cut and drives growth during a bulk. Hit your protein target first — every single day — then fill remaining calories with carbs and fat in whatever ratio works for you. Most people do better with higher carbs on training days (fuel performance) and higher fat on rest days (hormone support). IIFYM's flexibility doesn't mean "eat junk as long as numbers fit" — 80% of your intake should still come from whole foods for micronutrients, fiber, and satiety. The remaining 20% is where the flexibility lives.
IIFYM FAQ
What is IIFYM?
IIFYM (If It Fits Your Macros) is a flexible dieting approach where you track daily protein, carb, and fat grams rather than following a rigid meal plan. You can eat any foods you want as long as you hit your targets — making it more sustainable than traditional "clean eating" plans.
How much protein do I need per day?
For muscle building or retention during a cut, aim for 0.7–1.0g per pound of bodyweight (1.6–2.2g/kg). The body can't use more than ~1.2g/lb for muscle synthesis. Most people do well at 0.8g/lb as a practical target.
Which BMR formula should I use?
Use Mifflin-St Jeor for most people — it's the most validated. Use Katch-McArdle if you know your body fat percentage accurately (best for athletes and lean individuals). Harris-Benedict is the classic formula but slightly less accurate than Mifflin.
How do I split macros for fat loss?
A standard fat-loss split: 30–35% protein, 25–35% fat, 30–45% carbs. Keep protein high (0.8–1.0g/lb) to preserve muscle. Fat minimum is ~20% of calories for hormone health. Carbs fuel your workouts — don't go too low unless you're specifically doing keto.
How many calories to lose 1 pound per week?
One pound of fat = ~3,500 calories. A 500 calorie/day deficit produces ~1 lb/week loss. A 1,000 cal/day deficit = ~2 lbs/week. Most people do best losing 0.5–1% of bodyweight per week — anything faster risks muscle loss and metabolic adaptation.