IIFYM Calculator
IIFYM (If It Fits Your Macros) is a flexible dieting philosophy: any food is allowed as long as your daily protein, carbohydrate, and fat totals stay within budget. This calculator derives your TDEE from body stats and lets you fine-tune your macro split with adjustable sliders.
| Preset | Protein | Carbs | Fat |
|---|---|---|---|
| Standard | 30% | 40% | 30% |
| High protein | 40% | 30% | 30% |
| Low carb | 35% | 20% | 45% |
| Keto | 30% | 5% | 65% |
Unlike meal-plan diets, IIFYM sets daily macro budgets — not specific foods. You eat whatever fits. This flexibility improves long-term adherence compared to restrictive 'clean eating' plans.
Start with a preset (Standard 30/40/30 is a solid default). Increase protein if you're in a deficit to preserve muscle (35–40% works well). Drop carbs if you're insulin-sensitive or prefer a lower-carb approach. Never go below ~20% fat — it's required for hormones.
A 250–500 kcal deficit is a safe cutting range. More than 500 kcal/day increases the risk of muscle loss. For bulking, 250 kcal surplus ('lean bulk') minimises fat gain; 500 kcal is faster but adds more fat.
Set the meals slider to your typical number of eating occasions. Dividing daily targets into equal meals is the simplest starting point — the total is what matters, not meal timing.
- •Protein is the hardest macro to overeat and has the highest thermic effect (~25–30% of its calories are burned digesting it).
- •Track for 2 weeks before judging results — water weight and glycogen mask fat changes in the short term.
- •Use the Macro Cycling calculator (/macro-cycle) if you want different targets on training vs rest days.