Unit Price Calculator
The bigger box is not always the better deal. Type the price and the quantity for each option and the calculator divides one by the other to show the price per unit, then highlights the cheapest row in green. Set the unit name to whatever you buy by, whether that is ounces, rolls, sheets, or milliliters, and compare as many packages side by side as you like.
How to compare unit prices
- Set the Unit name field to what you measure by, such as oz, roll, sheet, or ml. It defaults to 'unit'.
- In the first row, type a Label, the total Price, and the Quantity in that package.
- Click '+ Add option' to add a row for every other package you want to weigh up.
- Read the 'Per unit' column: the lowest price per unit is highlighted green with a 'best' badge.
- Use 'Copy results' to grab the full per-unit breakdown, or the ✕ button to drop a row.
Examples
Small pack vs large pack
Option A: price 5, quantity 10. Option B: price 7, quantity 20.
A shows 0.5 per unit, B shows 0.35 per unit, so B is flagged best.
Paper towels priced by the roll
Unit 'roll'. 6-pack: price 12. 12-pack: price 18.
6-pack is 2.00 per roll, 12-pack is 1.50 per roll, best value the 12-pack.
Coffee priced by the ounce
Unit 'oz'. 12 oz bag: price 8.99. 32 oz bag: price 19.99.
12 oz is 0.7492 per oz, 32 oz is 0.6247 per oz, so the 32 oz bag wins.
Frequently asked questions
How is price per unit calculated?
It is the total price divided by the quantity. A pack priced 7 with a quantity of 20 works out to 0.35 per unit. Nothing else is factored in.
What counts as a unit?
Whatever you measure by: individual items, ounces, grams, sheets, rolls, or milliliters. The tool does not assume a unit, so set the Unit name field and keep it the same across every option you compare.
Why do small numbers show more decimal places than large ones?
Values of 1 or more are shown to two decimals, like 1.50. Values under 1 are shown to four decimals with trailing zeros trimmed, like 0.35 or 0.6247, so cheap per-unit prices stay distinguishable.
What if two packages have the same unit price?
Both rows are flagged best. When the cost per unit ties, decide on other grounds such as how much you will use before it expires, storage space, or brand preference.
How many options can I compare at once?
As many as you want. Start with the two default rows and click '+ Add option' for each extra package. The cheapest per-unit row is highlighted no matter how many you add.
Why can I not enter zero or a negative price or quantity?
A package needs a positive price and a positive quantity to have a meaningful cost per unit. Rows with blank, zero, or negative values are simply skipped rather than compared.
Does it convert between units for me?
No. It divides price by quantity exactly as typed, so convert first if one pack is in ounces and another in grams. Mixing units gives a meaningless comparison.
Does the tool send my numbers anywhere?
No. The comparison runs entirely in your browser with JavaScript. Nothing you type is uploaded, logged, or stored, so it works offline once the page has loaded.
Can I use it for anything besides groceries?
Yes. Any purchase measured in a repeating quantity works: printer paper by the sheet, cables by the meter, supplements by the capsule, or cloud storage by the gigabyte.
Learn more
- How to Compare Unit Prices and Spot the Real Bargain
A practical guide to price per unit: why bulk is not always cheaper, how to keep units consistent, and the traps that inflate the sticker deal.
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