Macro Calculator
Work out your daily calorie needs and macronutrient split (protein, carbs, fat) for a goal, check a diet-style ratio (balanced / keto / high-protein / low-fat), verify whether a nutrition label's numbers add up, or find a protein target based on bodyweight — with unit conversion, a mode-specific diagram, and a plain-language read on what the numbers mean.
Background
"Macros" are the three nutrients that supply energy: protein and carbohydrates each provide about 4 kcal/g, while fat provides about 9 kcal/g. Most macro planning starts from your BMR (Basal Metabolic Rate — energy burned at rest) via the Mifflin-St Jeor equation, scales it up to TDEE (Total Daily Energy Expenditure) using an activity multiplier, then nudges it up or down for a goal (lose, maintain, gain). From there, protein and fat are set first, and carbs fill in whatever calories are left.
How to use this calculator
- Pick a mode: Full Macro Plan, Diet Style Split, Food Label Checker, or Protein Target.
- The input fields change to match — fill in whatever the mode asks for, in whatever units you have.
- Click Calculate to see the result, a mode-specific diagram, step-by-step math, and a plain-language read on what the numbers mean.
- Try a quick pick to see a worked example instantly, including one deliberately extreme case per mode.
How this calculator works
Full Macro Plan: BMR is computed with the Mifflin-St Jeor equation, scaled to TDEE by an activity multiplier, then adjusted for your goal. Protein is set from grams per kg of bodyweight, fat is set to 25% of calories (never below an essential-fat floor of 0.6 g/kg), and carbs absorb whatever calories remain. The daily total is then split evenly across however many meals you eat.
Diet Style Split: your calorie target is multiplied by each macro's target percentage, then converted to grams using 4 kcal/g for protein and carbs, 9 kcal/g for fat.
Food Label Checker: grams of protein, carbs, and fat are converted back to calories (4/4/9 kcal per gram) and summed, then compared against the label's stated calories.
Protein Target: bodyweight is multiplied by a low and high grams-per-kilogram factor for your training focus, giving a target range instead of one rigid number.
All inputs are converted to base units first (kg, cm, kcal, g), so mixing lb with kg or in with cm is never a problem.
Formulas & Equations Used
BMR (male) = 10·weight(kg) + 6.25·height(cm) − 5·age + 5
BMR (female) = 10·weight(kg) + 6.25·height(cm) − 5·age − 161
TDEE = BMR × activity multiplier (1.2 - 1.9)
Goal Calories = TDEE × (1 + goal adjustment)
Protein (g) = protein-per-kg × weight(kg); Fat (g) = max(25% of calories ÷ 9, 0.6 × weight(kg)); Carbs (g) = remaining calories ÷ 4
Per-meal grams = daily grams ÷ meals per day
Diet-style grams = (calories × macro %) ÷ 4 or ÷ 9
Computed Calories = protein(g)×4 + carbs(g)×4 + fat(g)×9
Protein Target (g) = [low, high] g/kg × bodyweight(kg)
Identity: 1 g protein = 1 g carbohydrate = 4 kcal; 1 g fat = 9 kcal.
Example Problems & Step-by-Step Solutions
Example 1 — Full Macro Plan
Male, 30, 175cm, 80kg, sedentary, cutting.
Steps: BMR = 800+1093.75−150+5 = 1748.75. TDEE = 1748.75×1.2 = 2098.5. Goal = 2098.5×0.8 = 1678.8 kcal.
Result: ≈176g protein, 48g fat (floor), 135.7g carbs.
Example 2 — Diet Style Split
2000 kcal, Balanced (30/40/30) split.
Steps: Protein = 2000×0.30÷4 = 150g. Carbs = 2000×0.40÷4 = 200g. Fat = 2000×0.30÷9 ≈ 66.7g.
Result: 150g P / 200g C / 66.7g F.
Example 3 — Food Label Checker
Label: 210 kcal, 20g protein, 22g carbs, 8g fat.
Steps: Computed = 20×4 + 22×4 + 8×9 = 80+88+72 = 240 kcal. Diff = 240−210 = 30 kcal (14.3%).
Result: 240 kcal computed vs 210 stated — a modest, rounding-range gap.
Example 4 — Protein Target
70kg, Strength / Muscle Building focus (1.6-2.2 g/kg).
Steps: Low = 70×1.6 = 112g. High = 70×2.2 = 154g. Calories = 112×4 to 154×4.
Result: 112-154g protein/day (448-616 kcal from protein).
Frequently Asked Questions
Why does protein/fat get set first, and carbs last?
Protein and (to a lesser extent) fat have fairly fixed physiological needs — protein to preserve muscle, fat for hormones and vitamin absorption. Carbs are the most flexible macro, so they're the natural "remainder" once the other two are covered.
Why is there a fat floor?
Very low-calorie or very high-protein plans can push the 25%-of-calories fat estimate below what's needed for essential fatty acids and hormone production, so this calculator never lets fat drop under about 0.6 g per kg of bodyweight, even if that means carbs absorb less of the remaining calories.
Why do nutrition labels sometimes not add up exactly?
Labels round grams to the nearest gram (or half-gram) and calories to the nearest 5-10 kcal, so small gaps are normal. A large gap usually points to a rounding-friendly serving size, fiber/sugar-alcohol adjustments, or a genuine labeling error.
Why is the protein target a range, not one number?
Protein needs vary with training volume, calorie deficit size, and individual response — sports-nutrition guidance is almost always given as a range (like 1.6-2.2 g/kg) rather than a single value.
How does the per-meal breakdown work?
The Full Macro Plan divides your daily protein, carbs, and fat evenly by however many meals you select (1-6). It's a simple even split, not a smart distribution — some people prefer more protein earlier in the day or a bigger dinner, so treat it as a starting point to adjust from, not a rule.
Which diet style should I pick?
Balanced suits most general health and steady fat-loss/maintenance goals. High-Protein helps preserve muscle during a cut or support muscle growth. Low-Carb/Keto is fat-dominant and often used to promote ketosis for specific metabolic goals, though it takes an adjustment period. Low-Fat is carb-forward and sometimes used for specific medical protocols or personal preference. None is objectively "best" — the right one depends on your goal and what you can sustain.
Can I use kilograms and centimeters instead of pounds and inches?
Yes — every weight and height field has a unit dropdown (defaulted to lb/in, but switchable to kg/cm), and everything is converted internally before the math runs, so the result is identical either way.
Is this medical advice?
No. These are standard estimation formulas used in sports nutrition and fitness coaching, not individualized medical guidance. Anyone with a medical condition, pregnancy, or an eating disorder history should work with a doctor or registered dietitian.
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