Unit price calculator
Enter the price and quantity of two options in the same unit to see the price per unit for each, which one is the better deal, and the saving.
Option B is cheaper
$0.3122
12.67% less per oz than option A at $0.3575
How to use it
- Pick the unit both packages are measured in.
- Enter the price and the quantity for the first option.
- Enter the price and the quantity for the second option.
- Read which is cheaper per unit and by what percentage. If the saving is under a few percent, choose by what you'll actually use before it goes off.
Worked example
Coffee: a 12 oz bag for $4.29 against a 32 oz bag for $9.99.
12 oz bag: $4.29 ÷ 12 = $0.3575 an ounce. 32 oz bag: $9.99 ÷ 32 = $0.3122 an ounce.
The big bag is cheaper by $0.0453 an ounce, a 12.67% saving, as long as you’ll finish it while it’s fresh.
How this is calculated
The price per unit is the price divided by the quantity, kept to four decimal places so that small differences on cheap items don't round away. The cheaper option is the one with the lower unit price, and the saving is the difference as a share of the more expensive option's unit price. The comparison is only fair when both quantities are in the same unit, which is why the unit is picked once; if the shelf labels use different units, convert one with the unit converter first. Bigger isn't always cheaper: bulk sizes are often the better deal, but not reliably, and some stores price the mid size lowest.
unit price = price ÷ quantity, to four decimal places
difference = the higher unit price − the lower unit price
saving = difference ÷ the higher unit price × 100
Rates, sources and limits
Last reviewed 23 Sep 2026 by the CalcRabbit team. Estimates only, not financial, tax or medical advice.
Frequently asked questions
The shelf label already shows a unit price. Why calculate it?
Shelf labels often use different units for neighbouring products, per ounce on one and per pound or per 100 count on the next, which makes them useless for comparing. Entering both in the same unit fixes that. Labels are also sometimes wrong or missing on sale items.
What if the two products are in different units?
Convert one first. A 500 g bag against a 1 lb bag: 1 lb is 453.59 g, so enter both in grams. The unit converter on this site uses the exact factors.
Is the bigger size always the better deal?
No. Bulk sizes are usually cheaper per unit but not always, and stores sometimes price the middle size lowest or run a sale on the small one. And a cheaper unit price only saves money if you use it all: half a jumbo pack thrown away costs more than a small one finished.
Can I compare more than two?
Compare in pairs: put the winner of the first pair against the third option. Two quick rounds cover three products.