Macro Nutrient Flexible Diet Planner

🍗 Estimate your Total Daily Energy Expenditure with Mifflin-St Jeor, then split your target calories into flexible protein, fat, and carbohydrate targets with a meal-by-meal breakdown.

Energy & Macro Inputs

Leave blank to estimate from BMI using the Deurenberg formula.

1.6 g/kg lean mass (maintenance) 2.0 g/kg lean mass 2.2 g/kg lean mass (cutting)
25% (lower-fat split) 30% of calories 35% (keto-friendly)

Your Daily Macro Targets

BMR

—

kcal/day at complete rest

TDEE

—

kcal/day to hold weight

Target Calories

—

Goal adjustment

Lean Body Mass

—

used for the protein target

Macro Grams / day Calories / day % of Target Cal / gram
Protein — — — 4
Fat — — — 9
Carbs — — — 4

Meal Split Table

Meal Protein (g) Fat (g) Carbs (g) Calories

Per-meal grams are equal splits; adjust portions in practice to taste, schedule, and training timing.

Formula Breakdown 

Waiting for input…

⚠️ Not medical advice — this is an educational estimate using population formulas. Consult a qualified physician or registered dietitian before starting any diet or nutrition plan.

The Math Behind Flexible Macro Dieting

Understand the Mifflin-St Jeor equation, goal adjustments, lean-body-mass protein targets, and how carbs fill the remainder.

How The Formula Works

First, Basal Metabolic Rate is estimated with Mifflin-St Jeor: for men BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5; for women the constant is − 161. TDEE multiplies BMR by an activity factor (1.2–1.9). A goal adjustment then sets the calorie target: fat loss × 0.80, maintain × 1.00, or lean gain × 1.15.

Macro & Calorie Splitting

Protein carries 4 kcal/g, fat 9 kcal/g, and carbs 4 kcal/g. Protein is set at 1.6–2.2 g per kilogram of lean body mass (body weight minus body fat, estimated with the Deurenberg formula if not entered). Fat takes 25–35% of calories. Carbs = (target kcal − protein kcal − fat kcal) ÷ 4 fills the remainder. The meal-split table divides each gram target evenly across 3, 4, or 5 meals.

Troubleshooting & Edge-Case Failure Points

  • Unit conversion: pounds are divided by 2.20462 to become kilograms. Entering 75 in the pound field while thinking "kg" silently adds ~59 kg of mass to the equation.
  • Estimated body fat: the Deurenberg formula (1.2 × BMI + 0.23 × age − 10.8 × sex − 5.4) is a population estimate; very lean or very muscular individuals should enter a measured body-fat value for a more precise protein target.
  • Very low-carb check: if fat plus protein already exceeds the calorie target, carbohydrate grams go to zero and the tool warns instead of showing a negative number.
  • Activity overstatement: most people choose one tier too high. A "moderately active" desk worker who trains twice a week often overshoots by 300+ kcal/day.
  • Recalculation: after a 5–10 kg (10–20 lb) weight change, both BMR and lean mass shift enough to move targets — recompute the plan.

Step-by-Step Instructions

  1. Select your biological sex — it chooses the +5 or −161 constant in the Mifflin-St Jeor equation.
  2. Enter your age, weight (kg or lb), and height in centimetres.
  3. Pick an honest activity level and your calorie goal (fat loss, maintain, or lean gain).
  4. Optionally enter a measured body-fat percentage, or leave it blank for the automatic BMI-based estimate.
  5. Set your protein target (1.6–2.2 g/kg lean mass) and fat target (25–35% of calories); carbs fill the remainder automatically.
  6. Choose 3–5 meals, press "Calculate Macros", then copy your daily and per-meal targets.

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How to Use the Macro Diet Planner

Converts a calorie target and ratio into daily grams of protein, carbs, and fat — the arithmetic layer of every macro plan.

  1. Enter your calorie target (from the TDEE calculator: maintenance ± your goal delta).
  2. Pick a ratio or use the presets: balanced 30/40/30, lower-carb 35/25/40, higher-carb for endurance.
  3. Read grams per macro; hit protein first — it is the anchor.

The 4-4-9 Rule and Ratio Algebra

Protein & carbs = 4 kcal/g  |  fat = 9 kcal/g  |  alcohol = 7

Protein and carbohydrate carry 4 kcal/gram; fat carries 9. Worked example at 2,000 kcal on 30/40/30: protein 600 kcal ÷ 4 = 150 g; carbs 800 ÷ 4 = 200 g; fat 600 ÷ 9 = 67 g. The protein floor is the non-negotiable: research consensus centers on 1.6 g/kg bodyweight (0.7 g/lb) for active people building or defending muscle — set that first, then distribute the remaining calories by preference and training demands (endurance skews carbs; sedentary low-carb plans hold up well because fat is satiating). Alcohol at 7 kcal/g is the forgotten fourth macro — it is not free, and it suppresses fat oxidation while being metabolized.

Macro Diet Planner FAQ

How do I convert macros to calories?

Multiply grams: protein x4, carbs x4, fat x9. Reverse direction: divide the macro's calorie allotment by these factors.

How much protein do I need?

Around 1.6 g/kg (0.7 g/lb) for active people - the point where additional muscle-building benefit flattens. Set protein first, then fill with carbs/fat by preference.

Which ratio is best for fat loss?

Higher protein (30-40% of calories) preserves muscle in a deficit; the carb/fat split after that is mostly adherence. The best ratio is the one you keep.

Deep-dive guides