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Macro Calculator — IIFYM Calories & Macros Free

Calculate your daily calories, protein, carbs, and fat macros using the Mifflin-St Jeor formula. Set your goal — lose fat, maintain, or build muscle — free and accurate.

Macro Calculator

Che cos’è il Macro Calculator?

The Macro Calculator computes your personalized daily targets for protein, carbohydrates, and fat — the three macronutrients that provide all dietary energy. It uses the Mifflin-St Jeor equation (validated in a 1990 study in the Journal of the American Dietetic Association) to calculate your Basal Metabolic Rate (BMR), then multiplies by an activity factor to estimate your Total Daily Energy Expenditure (TDEE). From there, it applies a calorie adjustment based on your goal — fat loss, maintenance, or muscle gain — and distributes calories across macros using evidence-based protein targets from sports nutrition research.

This approach is the foundation of IIFYM (If It Fits Your Macros) — a flexible, evidence-based nutrition framework used by competitive athletes, bodybuilders, and recreational gym-goers alike. Unlike restrictive diet plans, IIFYM focuses on meeting specific nutrient targets within your calorie budget rather than eliminating food categories. Research consistently shows that IIFYM-style tracking produces equivalent or superior body composition outcomes compared to fixed meal plans, with better long-term adherence.

The calculator outputs your BMR (calories burned at rest), TDEE (total maintenance calories), goal-adjusted calorie target, and gram targets for protein, carbs, and fat — along with percentage breakdowns to visualize your macro split.

Formula Macro Calculator

Mifflin-St Jeor BMR: Men: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5 Women: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161 TDEE = BMR × Activity Multiplier Sedentary: × 1.200 Light: × 1.375 Moderate: × 1.550 Active: × 1.725 Very Active: × 1.900 Goal Adjustment: Lose Fat: TDEE × 0.80 (−20% deficit) Maintain: TDEE × 1.00 Build Muscle: TDEE × 1.10 (+10% surplus) Macro Split: Protein: Lose Fat = 2.0g/kg | Maintain = 1.6g/kg | Build = 2.2g/kg Fat: Lose Fat = 30% of cals | Maintain = 30% | Build = 25% Carbs: Remaining calories ÷ 4

Esempio Macro Calculator

Example 1 — Fat Loss: 30-year-old woman, 65 kg, 165 cm, moderately active (×1.55), goal: lose fat. BMR = 10×65 + 6.25×165 − 5×30 − 161 = 650 + 1031 − 150 − 161 = 1370 kcal TDEE = 1370 × 1.55 = 2124 kcal Target = 2124 × 0.80 = 1699 kcal Protein = 65 × 2.0 = 130g (520 kcal) Fat = 1699 × 0.30 / 9 = 57g (511 kcal) Carbs = (1699 − 520 − 511) / 4 = 167g

Example 2 — Muscle Building: 25-year-old man, 80 kg, 180 cm, very active (×1.725), goal: build muscle. BMR = 10×80 + 6.25×180 − 5×25 + 5 = 800 + 1125 − 125 + 5 = 1805 kcal TDEE = 1805 × 1.725 = 3114 kcal Target = 3114 × 1.10 = 3425 kcal Protein = 80 × 2.2 = 176g (704 kcal) Fat = 3425 × 0.25 / 9 = 95g (855 kcal) Carbs = (3425 − 704 − 855) / 4 = 467g

Come usare il Macro Calculator

  1. 1Enter your weight, height, age, and sex. These inputs feed the Mifflin-St Jeor formula to calculate your Basal Metabolic Rate (BMR) — the calories your body burns at complete rest.
  2. 2Select your activity level. Your TDEE is your BMR multiplied by an activity factor ranging from 1.2 (sedentary) to 1.9 (very active or physically demanding job). This is the calories you actually burn in a full day.
  3. 3Choose your goal. The calculator adjusts your calories by −20% for fat loss, 0% for maintenance, or +10% for muscle building, then distributes across protein, carbs, and fat using evidence-based targets from sports nutrition research. Your macro gram targets appear instantly.

Perché il Macro Calculator è importante

Tracking macronutrients — not just calories — is the most effective strategy for changing body composition. Total calorie balance determines whether you gain or lose weight, but the protein-to-calorie ratio determines how much of that weight change is fat vs. muscle. Research consistently shows that higher protein intakes (1.6–2.2 g/kg) during both deficits and surpluses significantly shift body composition toward lean mass compared to lower protein intake at the same total caloric intake.

Carbohydrates and fat serve different physiological roles: carbohydrates are the primary fuel for high-intensity exercise and glycogen replenishment; dietary fat is essential for hormonal function, fat-soluble vitamin absorption (A, D, E, K), and cell membrane integrity. Neither should be eliminated. The optimal split depends on your goal, training style, and individual preference — but hitting protein targets is non-negotiable for body composition.

For athletes and active individuals, precision nutrition produces measurable performance gains. A 2013 meta-analysis in the British Journal of Sports Medicine found that athletes who tracked macros (vs. eating ad libitum) maintained 2–3 kg more lean mass during cutting phases. For non-athletes, macro tracking prevents the common mistake of eating in a calorie deficit but consuming too little protein — causing weight loss that is 40–50% muscle rather than fat.

Limitazioni e Precisione

All macro calculators produce estimates, not prescriptions. The Mifflin-St Jeor formula has a 10% standard error in both directions — meaning your actual TDEE may be 200–400 kcal higher or lower than calculated. Factors not captured by the formula include: hormonal status (thyroid function, cortisol, estrogen/testosterone), gut microbiome efficiency, exact body composition (muscle burns more than fat at rest), and non-exercise activity thermogenesis (NEAT) — the unconscious movement that varies dramatically between individuals.

Adjust your targets based on 3-week real-world results. If following your calculated targets produces weight changes faster or slower than expected, your actual TDEE is different from the estimate — increase or decrease by 150–200 kcal accordingly. The numbers on this page are your starting point, not your ceiling. Metabolic adaptation also occurs during prolonged diets: TDEE decreases by 5–15% after 8–16 weeks of dieting, requiring periodic re-feeds or diet breaks to maintain caloric deficit.

Consigli Pratici

  • ✓Weigh food raw or cooked consistently — but never mix the two. A chicken breast weighs differently raw vs. cooked (shrinks ~25%). Pick one convention and stick to it. Raw is generally more accurate for tracking since cooked weight depends on cooking method and water retention.
  • ✓Aim to hit macros within ±5g for protein and ±10g for carbs and fat. Perfect precision is not necessary and adds stress. What matters is hitting your targets most days (5–6 out of 7) over weeks and months — not exact daily compliance.
  • ✓Use a food scale for at least 4–6 weeks. Eyeballing portions underestimates calories by 20–40% for most people, according to multiple studies. After tracking accurately for several months, most people develop portion size intuition and can reduce their reliance on the scale.
  • ✓Recalculate your macros every time your weight changes by 3–5 kg. As you lose or gain mass, your BMR shifts — what was a 20% deficit becomes a 15% deficit over time. Consistent recalculation maintains your desired rate of progress.

Frequently Asked Questions

How accurate is this macro calculator?
This calculator uses the Mifflin-St Jeor equation (1990), which is the most validated BMR formula for the general adult population. It predicts resting metabolic rate within 10% for approximately 82% of people — more accurate than the older Harris-Benedict formula. However, all formulas are estimates. Metabolic rate varies by genetics, hormonal status, gut microbiome, and body composition. Treat your result as a starting point and adjust by 100–200 kcal after 2 weeks based on actual weight trends.
Why is protein so high for fat loss?
During a calorie deficit, your body can break down muscle tissue for energy in addition to burning fat. High protein intake (2.0 g/kg for fat loss) significantly reduces this muscle loss — a process called muscle protein sparing. It also has a higher thermic effect (20–35% of protein calories are burned in digestion vs. 5–10% for carbs and fat) and produces greater satiety, helping control hunger. Multiple meta-analyses confirm that 1.8–2.2 g/kg is the optimal range for muscle preservation during fat loss.
Can I eat carbs and still lose fat?
Yes. Fat loss is determined by total caloric deficit, not by eliminating carbohydrates. Carbohydrates are your body's preferred fuel source for exercise, especially high-intensity training. Reducing carbs can help create a calorie deficit, but there is no metabolic advantage to low-carb diets beyond the calorie reduction they create. For most people, a balanced macro split that hits protein targets and maintains a calorie deficit will produce sustainable fat loss without the side effects of severe carb restriction.
What activity level should I choose if I go to the gym 3 times a week?
Choose 'Moderately active (3–5 days/week)' — this corresponds to an activity multiplier of 1.55. Many people underestimate their activity level; if you have a physical job or are on your feet much of the day in addition to gym sessions, 'Very active' (1.725) may be more appropriate. Activity multipliers are the largest source of error in TDEE calculations. If your weight is not changing as expected after 3 weeks, your estimated TDEE is likely off by 100–300 kcal.
How do I know if my macros are working?
Track your weekly average weight (weigh yourself daily at the same time and average the 7 readings). For fat loss: expect 0.3–1 kg loss per week. For muscle gain: 0.25–0.5 kg gain per week (at a beginner/intermediate level). If after 3 weeks you see no movement, adjust calories by 150–200 kcal in the appropriate direction. Also track how you feel — energy, sleep, performance in training. These are equally important signals.
Should I eat more on workout days vs. rest days?
Calorie and carb cycling is a real strategy, but it adds complexity. For most people, hitting consistent daily macro targets produces equivalent results with less cognitive overhead. If you train intensely 4+ days per week and want to optimize, a common approach is +10–15% carbs on training days and −10–15% on rest days while keeping weekly total equal. Protein should remain consistent every day.
What if I am a woman — are the targets different?
Yes. The Mifflin-St Jeor formula uses sex as an input — women have a lower intercept (−161 vs. +5 for men) because women naturally have lower muscle mass and higher fat mass relative to body weight, both of which reduce metabolic rate. The protein targets in this calculator are per kg of bodyweight and apply equally to men and women. Women may find that actual calorie needs are 200–400 kcal lower than calculated, especially if shorter or older. Adjust based on 2–3 week weight trends.

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Fonti Affidabili e Metodologia

↗World Health Organization (WHO) — Global health standards and BMI classifications
↗Centers for Disease Control (CDC) — US health guidelines and population data
↗National Institutes of Health (NIH) — Medical research and clinical guidelines
↗Mayo Clinic — Trusted clinical information and health advice

Accesso API

Prossimamente
https://api.solviqlab.com/v1/macro-calculator

REST API per sviluppatori. Integra questo strumento nella tua app.

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