How to keep a grocery price book

What to write down

One line per purchase, for the 20 to 30 things you buy most often. For each:

• Item, in plain words (“butter”, not the receipt's “SIG BTR SLTD”).
• Brand, and whether it's the store brand.
• Store and date.
• Size, with its unit (16 oz, 3 lb, 12 ct).
• Price paid, after any sale, before coupons you won't always have.
• Unit price: price divided by size. This is the number you compare. The unit price calculator does it for you.

How to use it

Find your “buy” price

After four or five entries for an item, the lowest unit price you've seen is your target. When you see it at or below that, buy enough to last until the next time it usually comes round.

See which store wins for which items

One store is rarely cheapest for everything. A price book usually shows a handful of items worth buying at the warehouse club, a few at the discount grocer, and the rest where it's convenient.

Catch price rises

Prices often creep up a little at a time. Writing them down is the only way most people notice an item that went from $3.49 to $3.99 over a few months.

Check the store brand

If you buy a name brand out of habit, note the store brand's price next to it once. Many households find a few staples where they can't tell the difference and the saving is real.

Paper, spreadsheet or app

• Paper is the classic: a small notebook or the printable below kept in the car.
• A spreadsheet sorts and does the unit-price math, but you still type every line.
• An app that reads your receipts skips the typing. Receipt Tree builds the price book from each receipt you scan and points out the store-brand, price-rise and cheaper-store savings for you.

Whichever you use, the habit matters more than the tool: write it down every trip, for a month.

Free printable price book page

Print as many copies as you need. Each page holds 14 lines.