Meal Prep Portion Math: Batch Cooking Chicken, Rice, and Vegetables by Calories and Protein
October 29, 2026
Meal prepping saves time and helps you stick to calorie and protein targets because the portions are measured in advance. The key calculation is the nutrition per portion: add the calories and macros of each ingredient in the container. Use cooked weights if you weigh the cooked food and raw weights if you weigh before cooking, but never mix them up, because food changes weight when cooked: chicken loses about 25% of its raw weight, while rice absorbs water and roughly triples.
Consider a meal with 150 g of cooked chicken breast (165 kcal and 31 g protein per 100 g), 200 g of cooked white rice (130 kcal and 2.7 g protein per 100 g), 150 g of steamed broccoli (35 kcal and 2.8 g protein per 100 g), and 1 tablespoon (14 g) of olive oil (119 kcal).
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Open the Macro Calculator →Calculating One Meal
Chicken: 150 g × 1.65 = 248 kcal; protein 150 × 0.31 = 46.5 g. Rice: 200 g × 1.30 = 260 kcal; protein 5.4 g. Broccoli: 150 g × 0.35 = 53 kcal; protein 4.2 g. Olive oil: 119 kcal; protein 0. Total: 248 + 260 + 53 + 119 = 680 kcal and 46.5 + 5.4 + 4.2 = 56 g protein. Carbohydrate: rice 200 × 0.28 = 56 g, broccoli 150 × 0.07 = 10 g, total about 66 g; fat: chicken 150 × 0.036 = 5.4 g plus oil 14 g plus small amounts = about 20 g. Adjust portions to hit your targets: remove the oil for 561 kcal, or add 50 g of rice for 65 more kcal.
| Ingredient (cooked) | Amount | Calories | Protein |
|---|---|---|---|
| Chicken breast | 150 g | 248 | 46.5 g |
| White rice | 200 g | 260 | 5.4 g |
| Broccoli | 150 g | 53 | 4.2 g |
| Olive oil | 14 g (1 tbsp) | 119 | 0 g |
| Total per meal | 680 | 56 g |
Scaling a Batch for Five Meals
For five meals, you need 750 g of cooked chicken (about 1,000 g raw, since 25% cooking loss: 750 ÷ 0.75), 1,000 g of cooked rice (roughly 330 g dry rice, as rice triples in weight), 750 g of broccoli, and 70 g of oil. Cook in bulk, then weigh the total cooked food and divide into five equal containers, which makes each portion exact even if the raw weights were approximate. The method: weigh the empty pot, weigh it again when full, subtract, and divide by the number of meals. This works for stews and casseroles where ingredients are mixed.
Raw vs. Cooked Weights
Nutrition databases list both. Chicken breast raw: about 120 kcal and 23 g protein per 100 g; cooked 165 kcal and 31 g. Dry rice: 365 kcal per 100 g; cooked 130 kcal. Dry pasta: 370 kcal; cooked 160. A common mistake is entering raw values for cooked food, which underestimates calories by up to 3 times for rice and pasta. Pick one convention for each food and stay consistent. Weighing raw is the most accurate because water absorption varies with cooking time.
Storage and Safety
Cool cooked food quickly and refrigerate within two hours. Store in airtight containers for up to 3 to 4 days in the refrigerator at or below 40°F (4°C); freeze portions that you won't eat within that time, for up to 2 to 3 months. Reheat to 165°F (74°C). Rice should be cooled quickly and not left at room temperature, because Bacillus cereus can produce toxins. Keep sauces separate when possible to prevent sogginess, and label containers with dates.
Frequently Asked Questions
How do I calculate calories for a meal prep container?
Add the calories of each ingredient by its weight, using consistent raw or cooked values.
How much weight does chicken lose when cooked?
About 25%.
How long does meal prep last in the fridge?
Generally 3 to 4 days.
How do I portion a mixed dish exactly?
Weigh the total cooked food and divide by the number of portions.
Why shouldn't I mix raw and cooked values?
Because cooking changes weight, which can cause large errors in calorie counts.