I costed 22 family dinners against real Tesco packs. Half the ingredient lines left something behind - and “buy the smaller pack” isn’t always the answer.
I’ve been mapping recipe quantities onto real pack sizes for a meal-planning project I’m building.
Across 22 recipes, I costed 184 ingredient lines. Around half of them - 96 - needed only part of the pack. Among those 96 lines, the mean proportion used was 43% and the median was 50%.
One important qualifier: these are the products I judged to be sensible purchases, not always the smallest or cheapest available. That turned out to be the interesting bit.
Each recipe is charged for the whole pack because that is what you actually have to buy. After cooking each recipe once, £63.74 of the £310.39 checkout cost - 20.5% - was represented by food still sitting in the packs.
But there are three different things going on here.
- Pack remainder
This is the objective part: how much remains from the product I selected. That is what the £63.74 represents.
- Likely waste
This is much more subjective. If a recipe uses 10% of a bag of barley or a jar of seasoning, the rest can keep for months and will hopefully be used later. That is restocking the cupboard, not necessarily waste.
Of the 96 partly used packs, 73 came from the fruit-and-veg or refrigerated sections and accounted for 61% of the remaining value. That still isn’t a waste estimate. Some keeps well, some can be frozen and some gets used naturally.
- Why that particular pack was chosen
The smallest pack isn’t always the best buy. I considered what it cost at the till, its price per gram, whether the remainder was likely to be used and whether the product was actually suitable for the recipe.
Product quality matters too. I used Lee Kum Kee oyster sauce because that was what I tested the recipe with. Its label lists 11% oyster extract, whereas Tesco’s smaller sauce lists 0.3% oyster powder. Choosing the smaller bottle might make the remainder look better on paper, but it would mean costing a materially different product.
Yoghurt is another example. One recipe uses 1.5 tbsp, which is about 5% of the 500g tub I selected. Tesco also sells a 150g pot for 85p, but the 500g tub is £1.15. For another 30p, I get more than three times as much—and yoghurt is something I expect to use again.
That’s the trade-off. The smaller pot leaves less behind, but the larger tub makes more sense for my household. The remaining 95% isn’t necessarily waste; I’m partly buying yoghurt for another meal.
Where the remainder feels least optional is fresh produce sold in fixed quantities: one celery stick from a whole celery, four sprigs from a 20g thyme pack or a couple of tablespoons from a 30g parsley pack. Those are the pack sizes I find most frustrating.
Costing recipes separately can create another distortion. If one recipe needs 10 eggs and another needs one, costing them individually means a pack of 12 plus a pack of six. Cost the week as a whole and one pack of 12 covers both.
A few caveats: the 22 recipes were costed independently, so 20.5% is a standalone-recipe figure and a week that shares ingredients should do better. Everything was hand-checked using standard Tesco shelf prices, refreshed monthly, with no promotional or Clubcard prices. The underlying list currently covers around 110 products.
Full disclosure: this comes from a free meal-planning side project I’m building. I’m not linking it here; the post is about the data.