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Unit Price Calculator: Compare Per-Ounce Cost

Use this unit price calculator to find the better deal between two packages — even when one is sold per ounce and the other per pound. Convert and compare in one step.

$
$
A — per unit$0.00
B — per unit$0.00
Better deal—
Savings (per unit)$0.00
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How this calculator works

Unit-price math is simple division — price ÷ quantity. The tricky part is making sure both products use the same unit. This tool auto-converts within a group (ounces, pounds, grams, kilograms all convert to ounces; ml and L convert to ml).

unit_price = total_price / quantity_in_common_unit

Most grocery stores already print a unit price on the shelf tag — typically in tiny font in the upper-left or lower-right corner. Look for "$X.XX per oz" or "per 100g". When two products are labeled in different units (a 12-oz bag vs a 2-lb bag), this calculator does the conversion.

Source: 19 U.S. states + DC require unit pricing on grocery shelves by law (Massachusetts, NY, NJ, CA among them). Federal guidance — FTC business guidance on pricing.

FAQ

When does the bigger size NOT win?
More often than you'd think. Family-size boxes of cereal, paper towels, and detergent are frequently 5–20% MORE expensive per unit than the medium size — especially when the medium is on promotion. Always check the shelf tag; don't assume bulk = cheaper.
What if one product is concentrated?
Adjust the quantity before comparing. A 32-oz concentrated dish soap that dilutes 2:1 effectively delivers 96 oz of usable product — enter 96 oz, not 32 oz. Same logic for laundry detergent, frozen juice, fertilizer.
How is unit price calculated?
Unit price = total price ÷ unit quantity. The trick is matching units. If A = $5 for 16 oz and B = $7 for 1.5 lb (= 24 oz), then A = $0.313/oz, B = $0.292/oz. B is cheaper per ounce.
Is the bigger size always cheaper per unit?
Usually yes, but not always. Grocery stores frequently price 'family size' at a HIGHER per-unit cost than the standard size — counting on shoppers assuming bigger = cheaper. Always check the per-unit price tag (most US states require it on grocery shelves) before grabbing the larger package.
Why do unit prices vary so much between stores?
Three factors: bulk discounts from suppliers, target customer demographics (Whole Foods vs Aldi), and store-level overhead. The same brand can vary 30-50% in unit price between stores. Costco and Aldi consistently lead on per-unit pricing.
Should I buy generic instead of brand to save more?
Almost always yes for staples. Generic flour, sugar, milk, OTC drugs, basic spices, and canned vegetables typically cost 30-50% less than name brands and are often manufactured in the same factory. Exceptions where brand matters: bacon, peanut butter, and high-end coffee.
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