Unit Price Calculator
Compare up to four package sizes by price per ounce, pound, 100 g, fluid ounce, liter or item, and see which is the better buy.
Unit price is the package price divided by its size. A 16 oz box at $3.49 costs about $0.218 per ounce, while a 32 oz box at $5.99 costs about $0.187 per ounce, so the bigger box is the better buy: the smaller one costs 16.5% more per ounce.
Unit prices are computed from the prices and sizes you enter and leave out anything added or taken off at the register, such as deposits, coupons or loyalty discounts. They compare cost per unit only, not quality, brand or how much of a larger package you will use, and a store's shelf label may round or choose units differently.
Unit prices, per ounce
- Item 1
- $0.218 per ounce16.5% more per unit than the lowest
- Item 2
- $0.187 per ounceLowest unit price
Under $1 shown to the tenth of a cent, $1 and up to the cent. Ranked on the exact value.
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About the Unit Price Calculator
Packages in different sizes are hard to compare on shelf price alone. The unit price puts them on the same footing: divide each price by its quantity and express it per ounce, pound, 100 g or whatever unit fits. A 16 oz box at $3.49 works out to $3.49 a pound, and a 32 oz box at $5.99 to $3.00 a pound, so the larger box saves about 14% per pound. The calculator converts between units exactly, which matters when one package is labeled in pounds and another in grams: $4.29 for a pound and $2.50 for 250 g come to $0.946 and $1.00 per 100 g. Rounding follows the unit pricing regulation credited below: a unit price of a dollar or more to the nearest cent, under a dollar to a tenth of a cent. Close calls are ranked on the exact figure, so 24 items for $12.99 and 12 for $6.49 both show $0.541 each, yet the 12-pack is the cheaper one by about 0.1%. A lower unit price is only a saving if you use the larger amount before it spoils.
Frequently asked questions
How do you calculate unit price?+
Divide the price by the quantity. $5.99 for 32 oz is 5.99 / 32 = $0.187 per ounce, and $3.49 for 16 oz is $0.218 per ounce. Use the same unit for every package you compare, or let the calculator convert them.
How do I compare a package in ounces with one in grams?+
Convert both to the same unit first. One ounce is exactly 28.349523125 g. The calculator does this for you: $4.29 for a pound and $2.50 for 250 g come to $0.946 and $1.00 per 100 g, so the pound is cheaper.
Why do two items show the same unit price but one is marked cheaper?+
Unit prices under a dollar are shown to a tenth of a cent, so two values can round to the same figure. The ranking uses the exact value: 24 for $12.99 and 12 for $6.49 both show $0.541, but the 12-pack is about 0.1% cheaper.
Is the biggest package always the best deal?+
No. Larger sizes are sometimes cheaper per unit, but not always, and sales can flip the order. A half gallon at $2.79 costs $5.58 per gallon, while a full gallon at $4.99 costs $4.99, yet a sale price can reverse that. Compare the unit prices each time.
Unit pricing terms and rounding: NIST Handbook 130 (2026), Uniform Unit Pricing Regulation, sections 2 and 4. Unit definitions: NIST Handbook 44, Appendix C.
By D.J. Gelner
D.J. Gelner is a direct-response marketer with 12+ years running growth for DTC and supplement brands, including VP-level roles. A former attorney, he builds and verifies the unit-economics math behind paid-media decisions daily.
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