Unit price calculator

Use this unit price calculator to compare up to eight package sizes. Mix grams with ounces or litres with fluid ounces, add multipacks, and see the cheapest option marked.

Free, no sign-up. Runs in your browser, with no AI calls.

Your figures

The filled values are an editable example. Results update as you type.

Currency changes formatting only. It does not convert amounts.

Packages to compare
Option A
Option B
Option C

Your calculation

Option B is the cheapest at $5.90 per 1 kg.

Price per unit
OptionQuantityPrice per 1 kgCompared with the cheapest
Option A$3.20500 g= 0.5 kg$6.408.47% more per unit$0.25 more for this amount
Option B$5.901 kg$5.90Cheapest
Option C$6.502 × 12 oz= 0.68 kg$9.5561.92% more per unit$2.49 more for this amount

Extra cost compares each package with buying the same amount at the cheapest unit price. Price per unit = price / (packs × size).

US units use the US customary definitions. A lower unit price only saves money if you use the whole amount.

Unit price is the package price divided by the quantity it contains. Convert every package to the same unit first, so 12 ounces and 500 grams compare fairly, and multiply the size by the number of packs in a multipack. The lowest price per unit is the cheapest way to buy that amount.

How to use this tool

Enter each package
For every option enter the price, the number of packs and the size of one pack with its unit. Quantity = packs × size, so a 4-pack of 330 ml cans holds 1,320 ml.
Convert to one unit
Weights convert through grams (1 oz = 28.3495 g, 1 lb = 453.592 g) and volumes through millilitres (1 US fl oz = 29.5735 ml, 1 US gallon = 3.78541 l). Comparing weight with volume needs the density of the product, so the calculator refuses to mix them.
Compare price per unit
Unit price = price / quantity, shown per the unit you choose, such as per kg or per ounce. Extra cost = package price - cheapest unit price × package quantity: what that option costs above the cheapest rate for the same amount.

NIST conversion factors for US customary units

Questions before you start

No. Promotions and multipack pricing can make a smaller size cheaper per unit than a bigger one. A lower unit price saves money only when you use the whole amount before it spoils or expires.

Grams measure weight and millilitres measure volume. Converting between them needs the density of the product, which differs between water, oil, flour and detergent. Compare packages labelled the same way, or look for a weight on the label of a liquid product.

US customary units: the avoirdupois ounce for weight, and the US fluid ounce, pint, quart and gallon for volume. UK imperial fluid ounces and gallons are different sizes, so convert those to millilitres or litres first.

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