IIFYM Macro Calculator

IIFYM stands for “If It Fits Your Macros.” An IIFYM calculator estimates your daily calorie target from your basal metabolic rate (BMR) and activity level, then converts that target into daily protein, fat, and carbohydrate grams. Instead of restricting specific foods, you can eat any foods you like as long as the day’s totals fit your macro targets.

First find your maintenance calories (TDEE). Then subtract about 20% to create a sustainable deficit. Set protein around 1.4–2.0 g per kg of body weight to protect muscle, set fat at 20–30% of calories, and fill the remaining calories with carbohydrates. This calculator performs all of those steps automatically.

There is no fixed carb target in IIFYM — carbohydrates get whatever calories remain after protein and fat are set. On a 2,500 kcal target with 150 g protein and 25% fat, that leaves about 300 g of carbs. If you prefer lower carbs, raise the fat slider and the calculator will recompute.

The International Society of Sports Nutrition (2017) recommends 1.4–2.0 g of protein per kg of body weight per day for exercising individuals, and up to 2.3–3.1 g/kg during calorie-restricted phases. This calculator defaults to 1.8 g/kg and lets you adjust between 1.2 and 2.6 g/kg with the protein slider.

The Institute of Medicine’s Acceptable Macronutrient Distribution Range puts fat at 20–35% of total calories, which is enough to support hormone production and vitamin absorption. This calculator defaults to 25% and lets you adjust between 15% and 40% with the fat slider.

IIFYM can support weight loss because it enforces the two things that matter most: a calorie deficit and adequate protein. Its flexibility often makes it easier to stick with than rigid meal plans. Results still depend on consistent tracking and adjusting based on your weight trend over 2–3 weeks.

A common starting point is roughly 30% protein, 20–25% fat, and 45–50% carbs by calories, but the ratio matters less than hitting your calorie target and eating enough protein. Use the sliders above to find a split you can sustain, then keep it consistent for a few weeks before judging it.

Keto and low-carb diets restrict carbohydrates specifically, while IIFYM only restricts total calories and sets minimum protein and fat targets. Carbs simply fill the remaining calories, so IIFYM can be high-carb, moderate-carb, or low-carb depending on your slider settings.

Formulas like Mifflin-St Jeor estimate resting metabolism within roughly 10% for most people, but individual metabolisms vary. Treat the results as a starting point: track your food and body weight for 2–3 weeks, then adjust calories up or down by 100–150 kcal based on your actual trend.

No. This tool provides educational estimates based on published formulas and is not medical, dietary, or professional advice. It is not suitable for children, pregnancy, eating-disorder recovery, or managing medical conditions — consult a doctor or registered dietitian for those situations.

The meal split table divides your daily macro targets evenly across 3, 4, or 5 meals, so you can see roughly how much protein, fat, and carbs to aim for at each meal. It is a planning convenience — total daily intake is what drives results, not exact per-meal equality.

Protein is set first because it has the strongest evidence behind it: it preserves muscle during fat loss and is the most satiating macronutrient. Fat is set second to cover essential needs, and carbohydrates take the flexible remainder, which is why IIFYM works with any eating style.