Unit Price Calculator: Compare Cost Per Unit Online

Unit Price Comparator

Enter the total price and the size of two products using the same measurement (for example, both in millilitres, grams, ounces, or pounds). The tool divides price by size to give a cost per unit so you can spot the better value in seconds.

Price of first item

Total you pay, e.g. 3.60 or 4.99 (USD, GBP, EUR, etc.)

Size of first item

Amount in the same units as the other row, e.g. 750 (ml) or 454 (g)

Price of second item

Total price of the competing pack

Size of second item

Size for the second pack in matching units

Sizes must be greater than zero.

How it works

Enter the total price and the size of two products using the same measurement (for example, both in millilitres, grams, ounces, or pounds). The tool divides price by size to give a cost per unit so you can spot the better value in seconds.

The Formula

Unit price = Total price ÷ Size
Example: £4.20 for 1000 ml → 4.20 ÷ 1000 = £0.0042 per ml
Lower unit price = better deal (same quality assumed).

Worked Example

Supermarket drinks
Offer A is £3.60 for 750 ml, so 3.60 ÷ 750 = £0.00480 per ml. Offer B is £4.20 for 1000 ml, so 4.20 ÷ 1000 = £0.00420 per ml. Offer B wins because each millilitre costs less—even though the bottle price is higher.

Tips, Assumptions & Limitations

Use the same unit for both rows (all ml, all g, or all oz).
If labels mix units, convert first (e.g. 1 L = 1000 ml) or use a length/weight converter on the site.
The better buy is the smaller cost per unit, not always the smaller total price.

FAQ

Put both sizes in the same unit. For example, use 500 and 1000 millilitres, or convert litres to millilitres first. The calculator only divides price by the number you type, so mixed units would skew the result.

Yes. Pick one currency for both prices. The tool only needs the numeric amounts; it reports a cost per unit in that same currency.

The smaller pack can cost less overall but more per millilitre or per gram. For the best value over time, choose the lower unit price unless you specifically need the smaller pack.