How to stop buying duplicate groceries

Two bottles of soy sauce, four cans of chickpeas, a third jar of cumin. Buying what you already have wastes money and shelf space, and the extras often expire before they're used. It usually comes down to a few causes - and a few habits fix them.

Why it happens

• You can't see it: things get pushed to the back of a deep shelf or freezer.
• You're shopping from memory, and memory says "I think we're out."
• More than one person shops, and nobody knows what the other bought.
• "Just in case" buying, especially when something's on sale.

Seven habits that stop it

1. Shop your pantry first. Before writing a list, look at what you have and plan a few meals around it.
2. Keep one list for the whole household. One shared list, added to as things run low, means nobody buys the same thing twice.
3. Make things visible. Clear bins, labels, and risers on deep shelves. Put new purchases behind the old ones (first in, first out).
4. Only write what's actually low. "Eggs" on the list should mean you checked and there are two left - not that eggs are a staple.
5. Give staples a "buy more at" point. Decide you restock rice when there's one bag left, and only then.
6. Keep a running inventory. Even a rough one beats memory, and it's what makes the other habits easy.
7. Check before you grab a deal. A sale is only a saving if you'll use it before it expires.