Look for the unit before comparing the number
Unit pricing lets you compare the cost of a consistent quantity, instead of judging only the price of the whole package. First check that two labels use the same unit and describe products you would actually substitute for one another.
NIST’s 2025 Unit Pricing Guide explains comparisons across brands and package sizes using a common measure. Its Mixed Units section addresses the need for consistent units when packages use different measures. This guide applies that basic idea to a shopping decision; it does not claim every store label follows identical rules.
A smaller number can use a different unit
“Per ounce” and “per pound” are different comparisons. So are weight ounces and fluid ounces. Do not compare two displayed numbers as though they describe the same quantity.
If converting units is inconvenient or the label is unclear, ask for help or compare packages with matching units. Leaving a comparison unresolved is preferable to guessing a result. A serving shown on a nutrition label is also not automatically the same unit used by the price label.
Use the price that applies to your purchase
A promotion may depend on a coupon, membership, quantity or another condition. Check whether you qualify and whether the advertised price applies to one item or a required group. Do not treat a conditional offer as your final price without reading it.
When a shelf label seems inconsistent with the package or promotion, ask the store to clarify. This worksheet is not a legal interpretation of pricing requirements or a live price checker.
Calculate a missing comparison
NDSU Extension’s unit-pricing guide gives the basic calculation: divide the item price by the item size. Keep the same measurement unit for both products.
An original example with hypothetical prices
Imagine two packages of the same dry ingredient:
| Package | Price you would pay | Amount | Calculation | Price per ounce |
|---|---|---|---|---|
| A | $3.60 | 12 ounces | $3.60 ÷ 12 | $0.30 |
| B | $6.00 | 24 ounces | $6.00 ÷ 24 | $0.25 |
These are invented prices for arithmetic practice, not current offers, a savings study or a recommendation for a brand. Package B costs less per ounce, but it also requires paying more at the checkout and buying more of the ingredient.
Keep enough precision to understand a close comparison, and notice that labels may display rounded values. Do not present a rough mental estimate as an exact result.
Decide whether the quantity fits your meals
University of Minnesota Extension’s unit-pricing page points out that a larger package may be a poor fit if much of it is discarded. A comparison is therefore a question about your plans as well as the price label.
Ask whether you want the amount, have appropriate space and know how it fits your meals. Do not invent an expiry date to justify a large purchase. Keep food-handling directions separate from the price calculation.
A smaller package can be the choice that fits your budget or current needs, even when its unit price is higher. The worksheet is a comparison aid, not a demand to optimize every item in the shop.
Copy the same-unit comparison sheet
| Question | Your note |
|---|---|
| Comparable product and package names | Paper note: __________________ |
| Quantity and measurement unit for each | Paper note: __________________ |
| Price and promotion conditions that apply | Paper note: __________________ |
| Common unit chosen for comparison | Paper note: __________________ |
| Calculation or clearly labeled estimate | Paper note: __________________ |
| Price per chosen unit for each product | Paper note: __________________ |
| Total checkout cost and quantity I want | Paper note: __________________ |
| Decision or question to clarify with the store | Paper note: __________________ |
Connect the comparison to the meals you intend to make
Start with a familiar ingredient on your shopping list rather than calculating every shelf. Build My Meals can provide its existing shopping list; it does not retrieve live prices, verify promotions or calculate a least-cost basket.
For planning the list itself, see the mix-and-match shopping guide. For known items already stored, the freezer inventory can help you record what is there without deciding food safety.