AJ Designer

Macro Calculator

kg
cm
years

Solution

—
Share:

How It Works

Macronutrients — protein, carbohydrates, and fat — are the calorie-yielding components of food. This calculator turns your body stats into a daily grams target in four steps. (1) Estimate basal metabolic rate (BMR) with Mifflin–St Jeor — Male: BMR = 10w + 6.25h − 5a + 5; Female: BMR = 10w + 6.25h − 5a − 161, where w is weight in kg, h is height in cm, and a is age in years. (2) Scale to TDEE by an activity factor (1.2 sedentary → 1.9 extra active). (3) Apply a goal multiplier (cut ×0.80, maintain ×1.00, bulk ×1.10) for the daily calorie target. (4) Convert kcal to grams using 4 kcal/g for protein and carbohydrates and 9 kcal/g for fat, multiplied by the percentage split you choose.

Example Problem

A 30-year-old male, 70 kg and 175 cm, exercises moderately 3–5 days per week and wants a 20% calorie deficit (cut) on a Balanced 30/40/30 macro split. What are his daily protein, carb, and fat targets in grams?

  1. Step 1 — BMR (Mifflin–St Jeor, male): BMR = 10 × 70 + 6.25 × 175 − 5 × 30 + 5 = 700 + 1,093.75 − 150 + 5 = 1,648.75 kcal/day.
  2. Step 2 — TDEE = BMR × 1.55 (moderate activity) = 1,648.75 × 1.55 = 2,555.56 kcal/day.
  3. Step 3 — Cut target = TDEE × 0.80 = 2,555.56 × 0.80 = 2,044.45 → round to 2,044 kcal/day.
  4. Step 4 — Macro grams on Balanced 30/40/30: protein 2,044 × 0.30 ÷ 4 ≈ 153 g; carbs 2,044 × 0.40 ÷ 4 ≈ 204 g; fat 2,044 × 0.30 ÷ 9 ≈ 68 g.
  5. Result: ~2,044 kcal/day with 153 g protein, 204 g carbs, and 68 g fat — adjust based on real-world weight trends over 2–4 weeks.

Key Concepts

The 4-4-9 energy densities (4 kcal/g for protein and carbohydrates, 9 kcal/g for fat) are the Atwater factors, the same coefficients on every nutrition label. Different macro splits suit different goals: Balanced 30/40/30 is a flexible all-purpose default, High Protein 40/30/30 prioritizes muscle retention on a cut, Endurance 25/55/20 fuels glycogen-heavy training with more carbs, Low Carb 30/20/50 fits insulin-sensitivity or appetite-control goals, and Keto 25/5/70 pushes the body into ketosis with under ~50 g of carbs per day. Protein around 1.6–2.2 g/kg body weight is well-supported for active adults regardless of split — total calories and protein matter more than the exact carb/fat ratio for body-composition outcomes.

Applications

  • Setting daily nutrition targets during a fat-loss cut, lean-bulk surplus, or maintenance phase.
  • Calibrating protein intake to preserve muscle mass during a calorie deficit.
  • Planning a ketogenic or low-carb day-to-day macro budget (keto preset: 25/5/70).
  • Building a fueling plan for endurance training (endurance preset: 25/55/20, ≈5 g/kg carbs).
  • Cross-checking the macros suggested by a dietitian, coach, or tracking app.

Common Mistakes

  • Treating the calculated number as exact. BMR equations carry ±10% error and activity factors are population averages — adjust based on real-world results, not the calculator output alone.
  • Setting protein too low on a cut. Higher protein (≈1.6–2.2 g/kg) protects muscle in a deficit; the High Protein 40/30/30 split is often more appropriate than Balanced for cutting.
  • Picking the highest activity factor because 'I work out'. The 1.9 multiplier is for laborers and serious athletes — most office workers who train 3–5×/week land at 1.55, not 1.725 or 1.9.
  • Confusing percentage with grams. A 30% protein share on a 2,000-kcal target is 150 g, but the same 30% on a 3,000-kcal target is 225 g — the percentage is constant, the grams scale with total calories.
  • Cutting too aggressively. Deficits beyond ~25% of TDEE accelerate muscle loss and metabolic adaptation; 10–20% is the sustainable range for most people.
  • Ignoring food quality. The calculator only sets totals — micronutrients, fiber, and food choices still matter for health beyond macro grams.

Frequently Asked Questions

What are macros?

Macros (short for macronutrients) are the three calorie-yielding components of food: protein, carbohydrates, and fat. Protein and carbs each provide 4 kcal per gram; fat provides 9 kcal per gram. Macro targets express your daily calorie goal as a split between these three nutrients in grams.

How do I calculate macros?

Four steps. (1) Estimate BMR with Mifflin–St Jeor. (2) Multiply by an activity factor (1.2–1.9) to get TDEE. (3) Apply a goal multiplier (cut ×0.80, maintain ×1.00, bulk ×1.10) for your daily calorie target. (4) Split that calorie target into protein/carbs/fat percentages and divide each by its energy density (4 kcal/g for protein and carbs, 9 kcal/g for fat) to get grams.

What's a good macro split?

Balanced 30/40/30 (protein/carbs/fat) is a flexible all-purpose default. For cutting, High Protein 40/30/30 protects muscle mass. For endurance athletes, 25/55/20 fuels training glycogen. For low-carb dieters, 30/20/50; for ketogenic dieters, 25/5/70 (with carbs typically under 50 g/day). There's no single 'best' split — total calories and adequate protein matter more than the exact carb/fat ratio for most people.

Should I eat more protein?

Most active adults benefit from 1.6–2.2 g of protein per kg of body weight per day for muscle protein synthesis and lean-mass retention — that's higher than the 0.8 g/kg RDA, which only prevents deficiency. On a cut, lean toward the upper end (1.8–2.2 g/kg). On a bulk or maintenance, 1.6–2.0 g/kg is plenty for most non-elite trainees.

Are keto macros healthy?

Short-term ketogenic eating (25/5/70 protein/carbs/fat with under ~50 g of carbs per day) is safe for most healthy adults and effective for weight loss, seizure control, and some metabolic conditions. Long-term effects on cardiovascular health, athletic performance, and metabolic flexibility are more debated. Talk to a doctor before starting keto if you have kidney disease, diabetes, or take blood-sugar or blood-pressure medication.

How many grams of protein per kg of body weight?

For sedentary adults, the RDA is 0.8 g/kg/day. For active adults aiming to build or preserve muscle, the evidence supports 1.6–2.2 g/kg/day — for a 70 kg person that's 112–154 g of protein per day. During an aggressive cut, push toward the upper end to protect lean mass.

What is the difference between macros and calories?

Calories are the total energy budget; macros are how that budget is divided between protein, carbs, and fat. Two diets at 2,000 kcal/day can have very different macros — e.g., 150 g protein + 200 g carbs + 67 g fat (balanced) vs. 125 g protein + 25 g carbs + 156 g fat (keto). Calories determine weight change; macros shape body composition and how the diet feels.

How often should I recalculate my macros?

Recalculate every 5–10 kg (10–20 lb) of body composition change, or every 4–6 weeks during an active cut or bulk. As body weight changes, BMR and TDEE change with it, and the original targets drift out of date. Also recalculate if your activity pattern changes — switching from desk job + 3 gym sessions to a manual job + 5 sessions shifts the activity factor.

Worked Examples

Fat-Loss Cut

How many grams of protein, carbs, and fat for a fat-loss cut?

A 30-year-old male, 70 kg and 175 cm, exercises moderately 3–5 days/week and wants a 20% deficit on a balanced 30/40/30 split. What are his daily macros for the cut?

  • Knowns: sex = male, w = 70 kg, h = 175 cm, a = 30 y, activity = moderate (1.55), goal = cut (×0.80), split = 30/40/30.
  • BMR (Mifflin–St Jeor) = 10·70 + 6.25·175 − 5·30 + 5 = 700 + 1,093.75 − 150 + 5 = 1,648.75 kcal/day.
  • TDEE = 1,648.75 × 1.55 = 2,555.56 kcal/day.
  • Cut target = 2,555.56 × 0.80 = 2,044.45 kcal/day → round to 2,044 kcal.
  • Macros: protein 2,044 × 0.30 ÷ 4 ≈ 153 g; carbs 2,044 × 0.40 ÷ 4 ≈ 204 g; fat 2,044 × 0.30 ÷ 9 ≈ 68 g.

~2,044 kcal/day — 153 g protein, 204 g carbs, 68 g fat

Track weight for 2–4 weeks; if loss is faster than 0.5–1% body weight per week, increase the calorie target by 100–200 kcal/day. Protein around 1.6–2.2 g/kg lean mass protects muscle during a deficit.

Lean Bulk

What macros does a young female lifter need to gain muscle?

A 25-year-old female lifter, 60 kg and 165 cm, trains hard 6 days/week. She wants a 10% calorie surplus on a high-protein 40/30/30 split to gain lean mass.

  • Knowns: sex = female, w = 60 kg, h = 165 cm, a = 25 y, activity = very (1.725), goal = bulk (×1.10), split = 40/30/30.
  • BMR = 10·60 + 6.25·165 − 5·25 − 161 = 600 + 1,031.25 − 125 − 161 = 1,345.25 kcal/day.
  • TDEE = 1,345.25 × 1.725 ≈ 2,320.56 kcal/day.
  • Bulk target ≈ 2,320.56 × 1.10 ≈ 2,552.62 kcal/day → round to 2,553 kcal.
  • Macros: protein 2,553 × 0.40 ÷ 4 ≈ 255 g; carbs 2,553 × 0.30 ÷ 4 ≈ 191 g; fat 2,553 × 0.30 ÷ 9 ≈ 85 g.

~2,553 kcal/day — 255 g protein, 191 g carbs, 85 g fat

A 10% surplus targets ~0.25–0.5% body weight gain per week, minimizing fat gain during a lean bulk. Reassess every 4 weeks — as body weight rises, BMR rises with it and the target needs a small bump up.

Endurance Maintenance

What does an endurance runner eat on a maintenance day?

A 35-year-old male marathon runner, 68 kg and 178 cm, trains very hard 6–7 days/week. On a no-deficit maintenance day, what should his macros look like on a 25/55/20 endurance split?

  • Knowns: sex = male, w = 68 kg, h = 178 cm, a = 35 y, activity = very (1.725), goal = maintain (×1.00), split = 25/55/20.
  • BMR = 10·68 + 6.25·178 − 5·35 + 5 = 680 + 1,112.5 − 175 + 5 = 1,622.5 kcal/day.
  • TDEE = 1,622.5 × 1.725 ≈ 2,798.81 kcal/day.
  • Maintenance target ≈ 2,798.81 × 1.00 ≈ 2,799 kcal/day.
  • Macros: protein 2,799 × 0.25 ÷ 4 ≈ 175 g; carbs 2,799 × 0.55 ÷ 4 ≈ 385 g; fat 2,799 × 0.20 ÷ 9 ≈ 62 g.

~2,799 kcal/day — 175 g protein, 385 g carbs, 62 g fat

Endurance athletes typically push carbs to 5–8 g/kg body weight on heavy training days to refill muscle glycogen. The 25/55/20 split fits the middle of that range; very long sessions (3+ hr) may justify carbs up to 10 g/kg.

Macro Calculator Formulas

The macro calculator strings together four steps. First it estimates resting metabolism (BMR) with the Mifflin–St Jeor equation, which is generally considered the most accurate prediction equation for healthy adults. Then it scales BMR by an activity factor for total daily energy expenditure (TDEE), applies a goal multiplier (cut, maintain, or bulk) for the daily calorie target, and finally converts kcal into grams using the standard 4-4-9 energy densities:

BMRmale = 10w + 6.25h − 5a + 5Mifflin–St Jeor (men)
BMRfemale = 10w + 6.25h − 5a − 161Mifflin–St Jeor (women)
TDEE = BMR × activity factor
Target = TDEE × goal factor (cut 0.80, maintain 1.00, bulk 1.10)
grams = (Target × split%) ÷ kcal/gprotein 4 kcal/g · carbs 4 kcal/g · fat 9 kcal/g

Where:

  • w — body weight in kilograms (kg)
  • h — standing height in centimeters (cm)
  • a — age in years
  • activity factor — 1.2 sedentary, 1.375 light, 1.55 moderate, 1.725 very active, 1.9 extra active
  • goal factor — 0.80 cut (≈ 20% deficit), 1.00 maintain, 1.10 lean bulk (≈ 10% surplus)
  • split% — share of total calories from each macro (presets: Balanced 30/40/30, High Protein 40/30/30, Endurance 25/55/20, Low Carb 30/20/50, Keto 25/5/70)

All prediction equations carry ±10% error vs. measured indirect calorimetry, and activity factors are population averages — your true maintenance calories may be 10–15% above or below the calculated target. Treat the macro split as a starting framework and adjust based on real-world results over 2–4 weeks. Protein should generally hover around 1.6–2.2 g/kg body weight for active adults regardless of split. This calculator is informational only and is not a substitute for clinical or dietitian-supervised advice.

Related Calculators

Related Sites