Meal Prep Portion Calculator
Work out exactly how much protein, carbohydrate and vegetables to buy and cook for your meal prep batch, based on your headcount and meal count - a shopping list, not a calorie count.
Calculator Inputs
Quantity Breakdown
| Category | Calculation | Amount |
|---|---|---|
| Protein | Enter your people and meals above | - |
| Carbohydrate | Enter your people and meals above | - |
| Vegetables | Enter your people and meals above | - |
| Freezer buffer meals | 20% of base servings, rounded up, if selected | - |
| Total Food Weight | Protein + Carbohydrate + Vegetables | - |
Scenario Analysis
| Scenario | Servings | Total Food | Protein |
|---|---|---|---|
| Your current plan | - | - | - |
| +1 extra person | - | - | - |
| Double the batch (freeze extra) | - | - | - |
| Larger portions instead of standard | - | - | - |
What Is A Meal Prep Portion Calculator?
A meal prep portion calculator turns your headcount and meal count into a shopping-ready quantity of protein, carbohydrate and vegetables, using published UK portion-size guidance instead of a guess. Enter how many people you are cooking for and how many meals you are prepping, and it returns a category-by-category weight breakdown plus how many containers to have ready. It is a quantity-planning tool: it does not calculate calories, macros or nutrient targets, and it is not dietary or nutrition advice.
How Does It Work?
The calculator starts from a per-person, per-meal reference weight for each food category - 120g of cooked meat or poultry, 140g of cooked fish, or 175g of cooked plant-based protein, plus a fixed 180g of carbohydrate and 160g of vegetables per meal - then multiplies by your total number of servings (people times meals) and your chosen portion-size tier (0.8x lighter, 1.0x standard, 1.25x larger). Every figure is shown with the calculation behind it in the Quantity Breakdown table.
Portion Size: Lighter, Standard Or Larger
The 120g/140g/175g protein weights sit at the standard 1.0x multiplier. Choosing lighter (0.8x) suits a smaller appetite or a lunch-sized portion - a 120g standard chicken portion becomes 96g. Choosing larger (1.25x) suits an active job or a bigger appetite - the same 120g portion becomes 150g. Every category scales by the same multiplier so the plate stays balanced at any size, rather than growing the protein while leaving carbohydrate and vegetables at the standard amount.
Batch Cooking And The Freezer Buffer
Batch cooking works best when the freezer portion is planned in from the start rather than added as an afterthought. This calculator's 20% buffer means a 10-meal batch becomes 12 meals, rounded up from the base servings figure, enough for two extra meals in the freezer without recalculating the whole shopping list by hand. WRAP's Love Food Hate Waste portion guide is one of the reasons UK households are encouraged to batch cook with a small planned surplus rather than cooking exactly to the day and discarding leftovers.
Storage And Food Safety
Getting the quantity right only helps if the food stays safe until you eat it. The Food Standards Agency's chilling guidance says cooked food should be cooled within about 2 hours and refrigerated below 8 degrees C; most cooked leftovers are then good for around 2 days in the fridge, or can be frozen for longer storage. If you add the freezer buffer, label each portion with the date it was cooked - a batch made on a Sunday is easy to lose track of by the following weekend.
Common Meal Prep Sizing Mistakes
The most common meal-prep sizing mistakes are treating a rough guess of a kilogram of chicken as good enough for any group size, forgetting that smaller appetites need roughly 80% of a standard adult portion rather than half, and under-buying vegetables because they look like the least important category. NHS Eatwell Guide portion thinking treats vegetables as roughly a third of the plate by volume, which is why this calculator's 160g vegetable reference sits close to the 180g carbohydrate reference rather than a token side amount.
Method And Limits
Method checked 6 August 2026. The formulas rest on four published UK portion-size references - the British Dietetic Association, the NHS Eatwell Guide, WRAP's Love Food Hate Waste guidance and the Food Standards Agency - scaled by however many people and meals you enter, then adjusted by a single portion multiplier and an optional 20% freezer buffer.
- Does not calculate calories, macros or nutrient targets. This is a quantity-planning tool, not a dietary or nutrition-advice tool. If you need calorie or macro tracking, a food-logging app is built for that job; this calculator only answers how much food you need.
- Does not account for allergies, intolerances or medical diets. Coeliac, low-FODMAP, kidney-diet and similar requirements change what you buy, not just how much - always check labels and, where a medical diet applies, confirm with a dietitian or GP.
- Assumes one protein type for the whole batch. It does not split a 10-meal batch into, say, 6 chicken meals and 4 lentil meals in one calculation - run it twice and add the results together instead.
- Does not price the shopping list. Costs vary too much by shop, brand and cut of meat to give a reliable UK-wide figure; this tool sizes quantities only.
- Reference weights are planning averages, not individual targets. Actual appetite varies by person, activity level and age; the 120g/140g/175g/180g/160g figures are the same kind of typical adult portion planning number the BDA and NHS guidance itself provides.
Figures checked .
Frequently Asked Questions
How much protein do I need per person per meal when meal prepping?
This calculator uses 120g of cooked meat or poultry, 140g of cooked fish, or 175g of cooked plant-based protein (beans, lentils, tofu) per person per meal, based on the British Dietetic Association's palm-sized portion guidance. Multiply that by your portion-size choice (0.8x lighter, 1.0x standard, 1.25x larger) and your total number of servings to get your total protein weight.
Why is the plant-based protein weight higher than meat?
Because pulses and tofu are less protein-dense by weight than meat, poultry or fish, so a portion that plays the same role on the plate weighs more - around 175g rather than 120g. This is a weight-for-weight substitution for portion planning, not a calorie or macro equivalence claim; the calculator does not calculate either.
How much rice or pasta should I cook per person?
The calculator uses a fixed 180g cooked-weight reference per meal per person, in line with the NHS Eatwell Guide's principle that starchy carbohydrates should make up just over a third of what you eat. This does not change with your protein choice, only with your portion-size selection.
How many vegetables do I need for meal prep?
160g per meal per person at the standard portion size - two 80g "5 A Day" portions, per NHS guidance. Choosing "larger" portion size raises this to 200g; "lighter" lowers it to 128g.
What does the freezer buffer actually add?
It adds 20% more meals on top of your base batch (people times meals), rounded up to the next whole meal. A base batch of 10 meals becomes 12; a base batch of 6 becomes 8 (6 times 1.2 = 7.2, rounded up to 8). It does not change your per-meal portion size, only the number of meals produced.
Does this calculator tell me how many calories I'm eating?
No. It is a quantity and shopping-list tool, not a calorie or macro calculator. If you need calorie tracking, use a dedicated nutrition app - this tool answers "how much food to buy and cook," not "how many calories is that."
Can I use this for a single person meal prepping for the week?
Yes. Enter 1 for people and however many meals you are prepping (commonly 5 for weekday lunches or dinners). The same per-meal reference weights and multipliers apply regardless of how many people you enter.
What if I'm cooking for a big group or an event, not repeat weekly meals?
This tool is built for repeat personal or household meal prep. For a one-off event with guests, CoryVu's Catering Quantity Calculator uses event-specific portion sizes (sit-down, buffet, canapes, BBQ) and adds drinks quantities, which this meal-prep tool does not cover. Above roughly 40 total servings, this calculator's Assessment module suggests switching to that tool.
Does portion size account for children?
Not directly with a dedicated input. Use the "lighter" 0.8x portion size as a reasonable starting point for a child's portion, then adjust to taste - children's appetites vary far more than the fixed halving some older catering guidance assumes.
How accurate are these portion weights?
They are UK planning references, not a measurement of your specific ingredients, recipe or appetite. The British Dietetic Association's own portion-size guidance and the NHS Eatwell Guide both present these as typical adult portions, not fixed rules - treat the calculator's output as a shopping-list starting point, not a precise recipe.
Do I need to weigh everything exactly?
No. The output is a shopping and batch-cooking guide in whole kilograms, not a recipe requiring gram-precision. Rounding to the nearest 100-250g at the shop is normal and the calculator's own figures are already planning averages rather than exact targets.
How long will my meal-prepped food last in the fridge or freezer?
The Food Standards Agency's guidance is to cool cooked food within about 2 hours, refrigerate it below 8 degrees C, and use most cooked leftovers within around 2 days, or freeze for longer storage. This calculator does not track use-by dates for you - label each container with the date it was cooked.
Can I mix protein types across my batch?
Not in a single calculation - the calculator assumes one main protein type per run. Run it twice (for example once with meat/poultry for half your meals, once with plant-based for the rest) and add the two results together for your full shopping list.
Does this work for lunches as well as dinners?
Yes. "Meals to prep" is a generic count of plated main courses; whether they are lunches, dinners, or a mix does not change the reference weights. Choosing "lighter" portion size is common for lunch-sized meals if you want a smaller container.
Why does a larger household need proportionally more of everything, not just more protein?
Because the underlying reference weights (120g protein, 180g carbohydrate, 160g vegetables per standard meal) are all per-person, per-meal figures. Doubling people or meals doubles total servings, and every category scales with total servings, keeping the same balanced plate ratio at any batch size.
Sources
- British Dietetic Association - Food Facts: Portion Sizes
- NHS - The Eatwell Guide
- Food Standards Agency - Chilling Guidance
- WRAP / Love Food Hate Waste - Food Portion Calculator
Last updated: 2026-08-06. This page gives an estimate only and is not medical, dietary or nutrition advice.