How to Make a Grocery Price Book
A grocery price book records what you usually pay for foods you buy often. For a dozen repeat purchases, note the package size and price, then work out the cost per ounce or item; add the store and date. Check that record when a sale tag claims a bargain.
Start with the foods that keep showing up
Open a recent grocery list and circle the items that appear almost every week. Rice, eggs, peanut butter, canned beans, oats, frozen peas. Pick ten to fifteen. Stop there. Your price book isn’t a catalog of the whole store, and you don’t need to record the price of a spice you replace twice a year.
Make one entry per food, not per brand. If you’ll eat either store-brand or name-brand oats, put both under "old-fashioned oats" so the comparison is easy to see. Add a note when a particular package size is the only one that fits your cupboard. Where would it go? A five-pound bag of rice isn’t a bargain if there’s nowhere dry to put it.
I think a small price book beats chasing every flyer. The flyer wants you to think about the sale; your list makes you think about dinner. For a starting point, use the last receipt you have, even if it only gives you the package price, then fill in the ounces from the package in your cupboard; if the receipt is gone, make the first few entries during your next ordinary shopping trip. Label the date and store. Prices move. An entry without a date eventually becomes a guess.
| Food | Size to record | What to write down | What you use it for |
|---|---|---|---|
| Old-fashioned oats | Ounces or pounds | Package price, price per ounce, store and date | Breakfasts you make often |
| Canned beans | Ounces per can | Price per can and price per ounce | Chili, soup or bean tacos |
| Rice | Pounds | Price per pound and package size | Bowls, sides and leftovers |
| Frozen vegetables | Ounces | Price per ounce and what’s in the bag | Fast dinners without a fresh-produce deadline |
| Eggs | Count per carton | Price per egg and carton size | Scrambles and baking |
Compare the amount you can actually use
The shelf tag’s big number is the price of the package, not a verdict on its value. Divide the package price by its weight or count, then compare like with like. This matters when one jar contains 18 ounces and the next contains 28. Match the units first. One tag might use pounds while the next uses ounces. Convert before deciding.
Here is illustrative U.S. price-book math, not current prices at any store. The dollar amounts are made-up examples for practicing the calculation, not quotes or a promise of what you’ll pay. For actual price changes, the USDA Economic Research Service Food Price Outlook, updated October 23, 2026 tracks national grocery inflation; it cannot tell you what a jar costs in your aisle today.
| Example item | Illustrative package prices | Unit-price math | Decision if you will use it |
|---|---|---|---|
| Peanut butter | 18 oz for about $3.60; 28 oz for about $5.04 | $3.60 ÷ 18 = about $0.20/oz; $5.04 ÷ 28 = about $0.18/oz | Larger jar costs more at checkout but less per ounce |
| Rice | 1 lb for about $1.80; 5 lb for about $7.50 | $1.80 ÷ 1 = about $1.80/lb; $7.50 ÷ 5 = about $1.50/lb | Larger bag works only if you’ll store and cook it |
| Canned beans | One can for about $1.05; four cans for about $3.80 | $1.05 ÷ 1 = about $1.05/can; $3.80 ÷ 4 = about $0.95/can | Four-pack fits if beans are already in your meals |
That peanut-butter difference is about two cents per ounce in this example. If you can’t cover the extra checkout cost, buy the smaller jar. The shelf tag can win the arithmetic and lose the week. You still need money for the other meals. And don’t compare drained beans with a dry-bean bag by weight alone: they’re different ingredients with different cooking work attached.
Give each entry a useful baseline
Keep the ordinary price and the best price you’ve actually seen, rather than writing "sale" with no number. For example, your note might say "rice, 5 lb, regular [your observed price], sale [your observed price], store, date." Next time the yellow shelf tag appears, check the unit price against that baseline. You can leave an old observation in place until you make the same purchase again; just don’t treat it as a current store price.
There’s a reason to date the entries. In the USDA’s October 2026 Food Price Outlook, the U.S. food-at-home CPI was 1.8% higher in September 2026 than in September 2025. That’s an average across grocery categories, not a claim about your particular cart. The same report says prices rose month to month in 11 of the 15 grocery categories it tracks, stayed flat in one and fell in three. A single old "good price" won’t stay useful for every food.
Don’t update all fifteen items on every trip. Record the two or three you buy that day, especially if you changed package sizes. A price book that takes five minutes after shopping will get used; a giant inventory of shelf tags probably won’t. If you shop two stores, keep both observations, but consider the whole errand: saving a few cents per ounce on rice at a second store may not be worth the extra trip when you still need to pick up the other items on your dinner list at the first one.
Let the meal plan decide what counts as a deal
Look in the fridge before you buy a second bag of anything perishable. Half a cabbage and two carrots are already waiting. Add leftover rice, and the practical purchase might be eggs for fried rice, not another bargain-sized box of greens. Start with the ingredients already at home, then check your price book for the missing ones. What you can make with what’s in your fridge offers ways to turn that inventory into meals.
You can also build a weekly budget grocery list before you shop. Mark the items you need for this week’s dinners and keep a separate "buy when the price is right" line for shelf-stable food. Three jars of sauce can wait. Your eggs and produce can’t, if they’re on the dinner plan.
A price book works especially well alongside unit-price comparisons at the grocery store. The shelf tag tells you which package is cheaper per ounce today. Your own notes tell you if today’s offer is better than what you’ve paid before. Two different questions. Keep both in view.
If you plan from your cupboard first, WattaEat lets you photograph your fridge, cupboard or freezer, check what it finds and set a weekly grocery budget. Its meal plan uses what you have first and makes an aisle-sorted list that skips those ingredients. Keep your personal price book for the prices you’ve actually seen; the app’s meal prices are estimates, not a receipt.
Make room for imperfect comparisons
Sometimes two packages aren’t the same food in practice. A bag of plain frozen spinach and a box of creamed spinach have different ingredients and uses; don’t put them on one price line just because both say spinach. For fresh herbs, ask if you’ll use the bunch in the meals you actually plan to cook this week; if the recipe calls for only a spoonful and you have no second use for the rest, the bigger bundle with the better price per ounce may leave you with an expensive pile of wilted parsley. For a bulk bag of dried beans, make sure you have time to cook them. Cheap on the shelf. Expensive in the trash.
For foods that need cold storage, use the FoodSafety.gov cold food storage chart rather than stretching storage time to make a bulk purchase feel worthwhile. If a package includes an allergen concern, check its label every time, including on a store-brand swap. A lower price doesn’t tell you anything about allergy safety.
Keep the note where you’ll see it in the aisle. Start with one screen. Put oats and beans there first, then add rice when you buy it. The next time you finish a bag of rice, write down the size, what you paid and the date before the receipt disappears. That’s your first real entry.
