Food Portion Size Calculator

Portion Size Guide

What should I know about Standard UK Portion Sizes?

NHS / BNF guidelines for adult main course portions: pasta (dry) 75–100g per person; rice (dry) 60–75g; potato (raw) 150–200g; chicken breast 120–150g; red meat 100–150g; fish fillet 120–150g; soup 300–400ml as main. These are for a normal appetite — athletes, manual workers, or those in calorie surplus may need 20–30% more. The NHS Eatwell Guide recommends one-third of the plate as starchy carbohydrates, one-third vegetables, and one-third protein.

What's the difference between Dry and Cooked Weight?

Pasta and rice absorb water significantly during cooking: 75g dry pasta becomes approximately 200g cooked. 60g dry rice becomes approximately 180g cooked. Meat loses moisture during cooking: 150g raw chicken breast becomes approximately 110g cooked. Always weigh dry/raw if tracking nutritional intake precisely — calorie information on packaging refers to the dry or raw weight unless specifically labelled as cooked. Cooking methods affect final weight: boiling retains less weight than baking.

What's the key thing to understand about Scaling for Groups?

For dinner parties and events: allow 10–20% extra for hungry eaters and second helpings — running out of food is more embarrassing than having leftovers. For pasta and rice, cooked leftovers refrigerate well for 2–3 days and reduce waste. For proteins, it is better to slightly under-cater on expensive items (steak, fish) and ensure generous carbohydrate and vegetable portions, as these are the most economical overflow options.

What's the key thing to understand about Reducing Food Waste?

UK households waste approximately £700 worth of food per year on average. Better portion sizing is the most direct reduction. Strategies: weigh ingredients before cooking rather than estimating (3 weeks of weighing builds intuition). Plan meals and cook to recipe rather than guessing. Batch cook when ingredients are near their use-by date. WRAP (Waste and Resources Action Programme) estimates UK households throw away 4.5 million tonnes of edible food annually — approximately 20% of all food purchased, much of it edible portions trimmed or discarded through oversized servings.

What should I know about Protein, Carb, and Vegetable Portion Balance?

Beyond simply calculating enough food per person, many standard healthy-eating guidelines (including the UK's Eatwell Guide) suggest a rough plate balance of about one quarter protein (meat, fish, eggs, or plant-based alternatives), one quarter starchy carbohydrate (potatoes, rice, pasta, bread), and around one half vegetables or salad. The per_person_g figure this calculator produces for a given food item is only one piece of that picture — if you're planning a full meal rather than just one component, it's worth running the protein, carbohydrate, and vegetable elements through separately and checking the resulting weights roughly follow that quarter-quarter-half pattern rather than one component dominating the plate. This balance matters for more than just calorie control: vegetables and whole grains contribute fiber and micronutrients that a protein-heavy or carb-heavy plate alone won't provide, and getting the proportions roughly right tends to produce meals that are both satisfying and nutritionally rounded without needing to count every calorie.

What should I know about Catering for Mixed Appetites?

Any single appetite setting applied evenly across a group will inevitably be slightly too much for some guests and slightly too little for others, since real appetite varies with age, activity level, and individual differences far more than a simple average suggests. Children typically eat meaningfully less than the adult portions this calculator is generally built around, while teenagers and very active adults can eat considerably more. For gatherings with a mixed group, a commonly used practical approach is to calculate for the number of adult-equivalent portions needed (counting young children as roughly half a portion, for example) and then add a buffer of around 10–15% on top of the calculated total_g, which comfortably covers larger appetites and modest seconds without drastically over-catering. This buffer approach is generally more reliable than simply rounding the per_person_g figure up for everyone, since that inflates every portion rather than just covering the uncertain margin, and tends to generate more food waste than a smaller, targeted buffer on the total.

What should I know about Portion Sizes for Children vs Adults?

Children's portion needs differ from adults' in ways that go beyond simple proportional scaling, since calorie and nutrient requirements vary by age, growth stage, and activity level rather than scaling neatly with body size alone. A common rough guide for young children (roughly 2-5 years) is to offer around half to two-thirds of an adult portion for starchy foods and protein, though appetite varies considerably day to day and portion guides should always flex to the individual child's hunger cues rather than enforcing a fixed amount. Older children and teenagers, particularly during growth spurts, can sometimes need portions close to or exceeding adult-sized servings, especially for energy-dense foods, reflecting genuinely higher calorie needs relative to body size during rapid growth. Rather than scaling every element of a meal down proportionally for children, it's generally better practice to offer smaller amounts of everything on the plate and let the child ask for more, which supports healthy appetite regulation better than pre-determining a fixed 'child portion' that may be too much or too little for that particular child on that particular day. When catering for a mixed group of adults and children, planning roughly one child portion for every one and a half to two adult portions is a reasonable starting estimate for calculating overall quantities needed.

Worked Example: Scaling a Dinner for Eight Guests

Standard UK adult portion guidance for a cooked protein such as chicken or beef is commonly cited as around 120-170g per person depending on appetite and cut, while cooked rice or pasta is typically around 180-220g per person and a mixed vegetable side around 80-100g per person. Worked example for 8 average-appetite adults: protein at 150g/person = 1.2kg; rice at 200g/person = 1.6kg (which, since rice roughly doubles in weight when cooked, means starting with about 800g of dry rice); vegetables at 90g/person = 720g. Scaling up for a known larger-appetite group, or scaling down modestly when children are included, are both straightforward multipliers applied to these same per-person baseline figures once the group's composition is known.

Visual Portion Guides When You Don't Have Scales

When cooking without weighing everything, hand-based visual guides are a widely used shortcut that scales naturally to the size of the person eating. A palm-sized, palm-thickness piece is a commonly used rough guide for a protein portion; a cupped handful is often used as a rough guide for a carbohydrate portion such as rice or pasta; and two cupped handfuls, or a fist-sized amount, is a common rough guide for a vegetable portion, roughly in line with the proportions promoted by balanced-plate guidance such as the UK's Eatwell Guide (which recommends filling around a third of the plate with vegetables or salad, around a third with starchy carbohydrates, and the remainder with protein and a small amount of dairy or alternatives). These are approximate visual shortcuts rather than precise measurements, useful for everyday cooking rather than situations needing exact portion control.

Adjusting Portions for Different Meal Occasions

The same food type can reasonably call for different portion sizes depending on whether it's a quick weekday lunch, a substantial evening meal, or part of a multi-course dinner where smaller individual portions are expected across several dishes. A starter-sized portion of a dish served as a main course elsewhere might run to roughly half the typical main-course weight, since appetite and the number of other dishes being served both factor into what counts as a satisfying amount. Planning portions with the specific occasion in mind, rather than applying one flat per-person figure to every meal context, reduces both the common failure modes of catering: running short, and over-preparing far more than will actually be eaten.

Why Leftover Planning Deserves Its Own Portion Calculation

Deliberately cooking for planned leftovers is a different calculation from cooking exactly enough for one sitting: rather than scaling a recipe to the group size alone, adding a known extra amount, often calculated as an extra half to full portion per person depending on how much leftover volume is wanted, turns the same cooking session into tomorrow's lunch without the waste or guesswork that comes from simply rounding up a recipe without a specific extra-portion target in mind.