Meal Prep Portions Calculator

Calculate per-meal macronutrient portions and total weekly prep quantities based on your calorie target and macro split.

Results

Visualization

How It Works

Meal Prep Portions divides a daily calorie target into per-meal grams of protein, carbohydrate, and fat using the Atwater factors (4 kcal/g protein, 4 kcal/g carbohydrate, 9 kcal/g fat), then scales by prep days for grocery quantities. The Acceptable Macronutrient Distribution Ranges (AMDR) from the National Academies of Medicine are 10-35% protein, 45-65% carbohydrate, and 20-35% fat of total kcal. The Recommended Dietary Allowance (RDA) for protein is 0.8 g/kg bodyweight; resistance-trained adults benefit from 1.6-2.2 g/kg per Morton et al. (Br J Sports Med, 2018). Per-meal protein doses of 0.4 g/kg (about 25-40 g for most adults) maximize muscle protein synthesis (Schoenfeld & Aragon, J Int Soc Sports Nutr, 2018).

The Formula

Protein (g/meal) = (Daily kcal x Protein%) / 4 / Meals Per Day Carbs (g/meal) = (Daily kcal x Carb%) / 4 / Meals Per Day Fat (g/meal) = (Daily kcal x Fat%) / 9 / Meals Per Day Weekly Total (g) = Daily Macro (g) x Prep Days

Variables

  • Daily kcal — Total calorie target per day
  • Protein%, Carb%, Fat% — Share of total calories from each macronutrient (must sum to 100; calculator auto-normalizes)
  • 4 kcal/g, 9 kcal/g — Atwater factors — energy density of protein/carb (4) and fat (9)
  • Meals Per Day — Number of eating events the daily target is divided into
  • Prep Days — Days the batch covers (used to compute total grocery quantities)

Worked Example

Worked scenario — 75 kg recreational lifter, 2,400 kcal target, 30/40/30 split, 4 meals/day, 5-day prep. Daily protein = 2,400 x 0.30 / 4 = 180 g (= 2.4 g/kg, well within Morton et al. range). Per meal = 180 / 4 = 45 g protein. Daily carbs = 2,400 x 0.40 / 4 = 240 g (= 60 g/meal). Daily fat = 2,400 x 0.30 / 9 = 80 g (= 20 g/meal). Five-day grocery list: 900 g protein (about 4.5 lb cooked chicken breast at 31 g protein per 100 g, or roughly 6.5 lb raw weight after 30% cooking shrink), 1,200 g carbs (about 5 cups dry rice yielding 15 cups cooked), and 400 g fat (about 470 mL olive oil or equivalent from whole-food sources).

Practical Tips

  • Cooked-vs-raw matters. USDA yield data shows chicken breast loses 25-30% weight cooking; raw 150 g portion equals about 105 g cooked. Weigh proteins cooked OR adjust raw target up by 30%.
  • Hit the 0.4 g/kg per-meal protein ceiling for muscle protein synthesis. A 70 kg person should aim for ~28 g protein per meal across 3-5 meals — going much higher per meal does not increase MPS further.
  • Refrigerated cooked protein is safe for 3-4 days at 40 F or below per USDA FSIS. For 5-7 day preps, freeze meals 4-7 in single-serving containers and thaw the night before.
  • Track cooking oil separately. A tablespoon (14 g) of olive oil is 120 kcal and 14 g fat — three pans of stir-fry can silently add 350+ kcal beyond what the calculator assumes from your ingredient targets.
  • Cooked white rice has a calorie density around 1.3 kcal/g; cooked chicken breast around 1.65 kcal/g. Building plates by weight (250 g rice + 150 g chicken + 200 g vegetables) is faster than tracking each ingredient.
  • Spread protein evenly. Three meals at 40 g beat one meal at 80 g + two at 20 g for muscle synthesis (Mamerow et al., J Nutr, 2014). Per-meal evenness matters more than total daily grams once total is met.
  • If macros sum below 100%, the calculator scales each up proportionally. This means 30/40/20 (sum 90) becomes 33.3/44.4/22.2 — your fat drops, not stays at 20%.

Frequently Asked Questions

Should my macro percentages always add up to 100%?

Yes. Protein, carbohydrate, and fat together account for essentially all dietary energy (alcohol contributes 7 kcal/g but is not a macronutrient and is not tracked here). The calculator normalizes inputs proportionally if they do not sum to 100, but planning to exactly 100 produces cleaner numbers and matches how dietitians typically prescribe macro splits.

What macro split should I pick?

Within the AMDR (10-35% protein, 45-65% carb, 20-35% fat), most healthy adults do well at 25-30% protein, 40-50% carb, 25-30% fat. Resistance-trained athletes often run 30-35% protein. Endurance athletes may push carbs to 55-60%. Ketogenic diets sit outside AMDR at roughly 70-75% fat, 20% protein, 5-10% carb. Pick based on training type and what you can sustain — adherence beats optimization.

How long do prepped meals stay safe in the fridge?

USDA Food Safety and Inspection Service guidelines: cooked meat, poultry, and seafood are safe 3-4 days at 40 F (4 C) or below. Cooked grains and legumes are similar. Past day 4, freeze. Reheat to 165 F internal temperature before eating to kill any organisms that grew during storage.

Why 4 kcal/g for protein and carbs but 9 for fat?

These are the Atwater factors, established by Wilbur Atwater in the late 1800s through bomb calorimetry. Fat packs 2.25x the energy per gram because it contains less oxygen than carbohydrate or protein, so more energy is released during oxidation. Modern food labeling uses these same factors with minor adjustments — they are accurate to within ~5% for most foods.

Can I redistribute the per-meal portions unevenly?

Yes. The calculator outputs equal splits for simplicity but most people eat asymmetrically — bigger lunch, smaller snack, etc. Treat the per-meal values as a daily budget. The only constraint worth respecting: keep individual protein meals at or above 0.4 g/kg bodyweight (about 25-40 g) to maximize muscle protein synthesis.

Does meal prep work for losing weight?

Meal prep itself does not cause weight loss — energy balance does. Prep helps because pre-portioned meals reduce decision fatigue and limit unplanned eating, which is where most people overshoot. Studies show meal-replacement and structured meal programs produce roughly 5-7% greater weight loss at 12 months versus self-directed dieting (Heymsfield et al., Int J Obes, 2003).

How do I scale this for a couple or family?

Multiply weekly totals by the number of people if everyone follows the same target. For mismatched targets (e.g., 1,800 kcal partner + 2,500 kcal partner), run the calculator twice and combine the grocery lists. Cooking time barely scales — making 8 portions takes maybe 30% longer than making 4.

What about cooking shrinkage when I weigh ingredients raw?

Most proteins lose 20-35% weight during cooking (water loss). USDA yield factors: chicken breast 28%, ground beef 25%, salmon 20%, lean beef 30%. Rice gains weight (1 cup dry yields ~3 cups cooked) because it absorbs water. Either weigh cooked and use cooked nutrition data, or weigh raw and apply yield factors. Mixing the two underdoses or overdoses your portions.

Sources

Last updated: May 04, 2026 · Last reviewed: May 2026 — NutritionCalcs Editorial Team · About our methodology

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