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
The Meal Prep Portions Calculator divides your daily calorie and macronutrient targets into equal per-meal portions, then multiplies by your prep days to give you exact grocery quantities. This eliminates guesswork and food waste when batch-cooking meals for the week.
The Formula
Variables
- Daily Calories — Your total calorie target per day in kcal
- Protein% — Percentage of calories from protein (4 kcal per gram)
- Carb% — Percentage of calories from carbohydrates (4 kcal per gram)
- Fat% — Percentage of calories from fat (9 kcal per gram)
- Meals Per Day — Number of meals you eat each day
- Prep Days — Number of days you are prepping meals for
Worked Example
For a 2,000 kcal target with a 30/40/30 macro split across 4 meals: Protein per meal = (2000 x 0.30) / 4 / 4 = 37.5 g. Carbs per meal = (2000 x 0.40) / 4 / 4 = 50 g. Fat per meal = (2000 x 0.30) / 9 / 4 = 16.7 g. Over 5 prep days that is 20 total meals requiring 750 g protein, 1,000 g carbs, and 333 g fat.
Practical Tips
- Keep your macro percentages adding to 100%. The calculator auto-normalizes if they don't, but planning to 100% gives cleaner numbers.
- Weigh cooked protein sources on a food scale for accuracy. Eyeballing portions can be off by 30-50%.
- Prep starchy carbs (rice, potatoes) and proteins separately so you can mix and match throughout the week.
- Store prepped meals in clear containers labeled with the macro content so you can grab and go.
- If your fat percentage feels low per meal, remember cooking oils and dressings add fat that may not be counted in the base ingredient.
Frequently Asked Questions
Should my macro percentages always add up to 100%?
Ideally yes. The three macronutrients account for all caloric intake, so protein, carbs, and fat percentages should total 100%. If your inputs don't add to 100%, the calculator normalizes them proportionally so the math still works.
How do I know what macro split to use?
A balanced starting point is 30% protein, 40% carbs, 30% fat. Athletes or those building muscle may go higher protein (35-40%). Low-carb dieters might use 40% fat, 30% protein, 30% carbs. Consult a dietitian for personalized ratios.
Can I prep meals for a full 7 days?
You can, but food safety guidelines suggest consuming prepped meals within 3-4 days when refrigerated. For 5-7 day preps, freeze the later-day meals and thaw them the night before eating.
Why does the calculator use 4 calories per gram for protein and carbs but 9 for fat?
These are the Atwater factors, the standard energy values used in nutrition science. Protein and carbohydrates each provide about 4 kilocalories per gram, while fat provides about 9 kilocalories per gram. Alcohol provides 7 kcal/g but is not a macronutrient.
Is it okay to have different-sized meals instead of equal portions?
Absolutely. This calculator gives equal splits for simplicity, but many people prefer a larger lunch and smaller snacks. Use the per-meal values as a daily budget and redistribute as you like, keeping the daily totals the same.