Shopping Lists

Why your shopping list says "200g of onion" twice

Half an onion, 100g of diced onion, one medium onion — three recipes, three units, three separate lines. Here's why recipe ingredients don't merge on their own.

Plan a few recipes for the week and build a shopping list from them, and a small but annoying problem shows up almost immediately: the same ingredient listed separately for each recipe that uses it, in whatever unit that particular recipe happened to use. One recipe calls for half an onion, another for 100g of diced onion, a third for "one medium onion." On the list, that becomes three separate entries, none of them obviously the same thing, none of them telling you whether one onion actually covers it or you need to buy more than one.

Why this happens

Recipes aren't written with a shared standard for how ingredients get measured — one author works in grams, another in cups or whole items, a third in a mix depending on the ingredient. That's fine recipe by recipe, but it becomes a problem the moment several recipes' ingredient lists get combined into one shopping list, because nothing automatically recognises that "half an onion," "100g diced onion," and "1 medium onion" are all pointing at the same item.

Left unmerged, a list ends up longer and more confusing than it needs to be, and it pushes the actual conversion work back onto whoever's shopping — doing rough maths in the aisle to figure out whether three line items for onion mean one onion or three.

It pushes the conversion work back onto whoever's shopping — rough maths in the aisle to figure out whether three line items for onion mean one onion or three.

Why this is worse than it sounds

Beyond just being a slightly annoying list to read, unmerged quantities are a direct cause of some of the small overspending covered elsewhere — buying more than needed because the list implied several separate purchases rather than one combined one, or under-buying because it wasn't obvious the quantities needed adding together at all.

What a properly consolidated list needs to do

• Recognise the same ingredient across different recipes, even when each recipe measured it differently
• Convert between compatible units so quantities can actually be added together, not just listed side by side
• Present one combined line per ingredient, with an actual total, rather than several entries requiring manual addition

Where mmmiso fits

The shopping list consolidates matching ingredients across the week's recipes, so "half an onion," "100g diced onion" and "1 medium onion" don't show up as three separate lines. Weights, volumes and common countable items are converted and combined into one total per ingredient. Where it has to turn a count into a weight, it uses an average size (an onion counts as roughly 150g), so treat those totals as a close estimate rather than an exact figure. For items it has no average for, it keeps the lines separate rather than guessing. Either way, there's less mental maths in the vegetable aisle.