Grocery Price Book: A Simple Template for Comparing Prices
Build a grocery price book with a copyable table, unit-price calculations, and examples for discounts, multipacks, and shrinking package sizes.
A grocery price book is a record of what you paid for comparable products, including the store, date, package size, and unit price. It helps you judge a price against your own purchase history instead of relying on a “sale” label or memory.
The key field is not the price on the packet. It is the price for a consistent quantity: per kilogram, ounce, liter, or item, depending on what you are buying.
You can build a useful price book in a notebook or spreadsheet. Start with products you buy repeatedly, not every item in the supermarket.
Record quantities as carefully as prices
NIST explains unit pricing as expressing cost per unit of measure so shoppers can compare value. That is also the foundation of a price book.
A $3 packet and a $4 packet are not directly comparable until you know their contents. Likewise, an old receipt showing the same packet price does not tell you whether the package has become smaller.
For each observation, record the product and variant, store, purchase date, package quantity, amount paid, and any discount conditions. Then calculate the unit price. Keep enough detail to distinguish genuinely comparable items without turning the record into a product catalog.
For example, plain rolled oats and a flavored breakfast mix may have different uses for your household. Their prices per kilogram are comparable mathematically, but that does not make them interchangeable purchases.
Copy this grocery price book template
The following prices and stores are illustrative. They are not current market prices, actual BudJet customer purchases, or promises of savings.
| Date | Product and variant | Store | Total quantity | Amount paid | Unit price | Conditions |
|---|---|---|---|---|---|---|
| Sep 20 | Plain rolled oats | Store A | 750 g | $2.40 | $3.20/kg | Regular price |
| Sep 22 | Comparable plain rolled oats | Store B | 1 kg | $3.60 | $3.60/kg | Regular price |
| Sep 24 | Comparable plain rolled oats | Store C | 2 × 500 g | $3.00 | $3.00/kg | Must buy two |
| YYYY-MM-DD | Product and variant | Store | Quantity and unit | Amount | Price per unit | Discount or other condition |
Store C has the lowest observed unit price in this example. It also requires buying two packets. Store A requires less money at checkout. Which is the more useful purchase depends on available cash, how much you need, and whether you will use it.
Do not turn an old entry into a claim about today's price. The date is part of the comparison, not decoration.
Calculate unit prices without mixing units
Use this formula:
Unit price = amount paid ÷ total quantity in the comparison unit.
For the first row, 750 g is 0.75 kg. The calculation is $2.40 ÷ 0.75 = $3.20 per kg.
For the multipack, two 500 g packets contain 1 kg in total. The calculation is $3.00 ÷ 1 = $3.00 per kg. Dividing by 500 g would wrongly double its apparent unit price.
You can use dollars per ounce instead, or another currency. What matters is matching units within a comparison. Keep weight, volume, and count separate: fluid ounces and weight ounces are not interchangeable, and a liter cannot be treated as a kilogram without additional information.
Choose a useful unit for each type of product. Eggs might be compared per egg of a similar size; oil per liter; rice per kilogram. For products whose performance or concentration differs, quantity alone may not settle which offers better value.
Record the conditions behind a discount
A low number is not very informative if it required a membership, coupon, minimum spend, or purchase quantity you cannot reproduce.
Record the amount actually paid after an item-specific discount. Keep deposits and delivery charges separate when comparing product prices. Be consistent about whether your comparison includes tax; mixing tax-inclusive and tax-exclusive observations will distort the result.
For a basket-wide coupon, either allocate it using a documented method or keep it as a basket adjustment. Do not attribute the entire coupon to every product.
It can also help to keep the undiscounted product price alongside the amount paid. That separates a one-off promotion from the regular price you are likely to see again.
A loyalty price may be perfectly useful to you. Labeling the condition simply prevents it from being confused with an unconditional price.
Use the price book to spot smaller packages
Suppose a product costs $4.00 for 500 g, then remains $4.00 but changes to 450 g. These are hypothetical figures.
| Observation | Price | Package size | Price per kilogram |
|---|---|---|---|
| Earlier package | $4.00 | 500 g | $8.00 |
| Later package | $4.00 | 450 g | About $8.89 |
The packet contains 10% less, but the unit price has increased by about 11.1%: (8.888… ÷ 8 − 1) × 100.
A record containing only “product, $4.00” would miss that change. NIST describes reduced contents at an unchanged product price as shrinkflation in its unit-pricing guidance.
Check that you are comparing the same product or a clearly identified replacement. A different flavor, formulation, or pack type is not automatically evidence that the original product shrank.
Turn the record into a shopping decision
Before buying a recurring item, compare the current unit price with recent, relevant observations. Ask whether the item is equivalent, whether the deal's conditions apply to you, and whether the quantity fits your needs.
Do not build your plan around the lowest price you saw two years ago. Keep a recent regular-price reference and label exceptional deals separately.
Consider the whole trip, too. A lower unit price at another store is not automatically worth a separate journey. Compare the realistic basket difference with transport costs and the value of your time.
Nor is the biggest pack automatically the economical choice. In a hypothetical example, paying $6 for 2 kg but using only 1 kg makes the purchase cost $6 per kilogram actually used. A 1 kg pack costing $4.50 would cost less for that use. That is not a food-waste statistic; it is a reminder to include your likely use in the decision.
What receipts can—and cannot—supply
Receipts are useful evidence of what was paid and when. They may not provide a readable brand, full package weight, or all the information needed to compare variants. Add those details from the packaging when necessary.
A scanner can also confuse a quantity, a unit price, and the total for a line. Check those fields before calculating a price history. Saving a well-formatted but incorrect number makes future comparisons less useful.
BudJet extracts receipt items, prices, and available quantity information, with suggested categories. You can
Keep the two questions separate:
Common questions
How many products should I track?
Start with a small group of recurring purchases that matter to your spending. Add products when the comparison could change a decision. A maintained record of ten useful items is more actionable than hundreds of incomplete entries.
Does a price book need an app?
No. A notebook or spreadsheet with dates, quantities, prices, and consistent units is enough. An app is helpful when its capture or organization features make the record easier to maintain.
Does the lowest unit price always mean the best purchase?
No. Affordability today, product suitability, storage, travel, and the amount you will actually use still matter. Unit price gives you one clear comparison; it does not make the entire decision.