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.
Total you pay, e.g. 3.60 or 4.99 (USD, GBP, EUR, etc.)
Amount in the same units as the other row, e.g. 750 (ml) or 454 (g)
Total price of the competing pack
Size for the second pack in matching units
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.
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).
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.
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.
Shoppers in the US and UK often face two prices that are hard to eyeball: a smaller pack that looks cheaper at the till versus a larger pack with a higher sticker price. Unit pricing divides total price by the amount you get—millilitres, grams, fluid ounces, or pounds—so you can judge fairness the same way a classroom ratio problem does.
Retail labels sometimes highlight multi-buys or loyalty prices, but the decisive number for value is still cost per unit. When both items are measured with the same unit, dividing price by size removes the distraction of pack shape or brand claims. This mental model is standard consumer mathematics: it is educational only and does not replace reading the full label, checking quality, or budgeting choices that depend on how much you can store.
Unit price = Total price ÷ Size (using identical units for both products). If unit price A is less than unit price B, offer A is the better value on a per-unit basis.
Imagine a £3.60 bottle with 750 ml and a £4.20 bottle with 1000 ml. The first costs 3.60 ÷ 750 = £0.00480 per ml; the second costs 4.20 ÷ 1000 = £0.00420 per ml. The larger bottle wins on unit price. In dollars, the same arithmetic applies: $5.49 for 12 fl oz versus $7.99 for 20 fl oz—convert both to the same volume unit first, then divide.
Open the Unit Price Comparator on the tool page and type price and size for each offer in the same measure. Use plain numbers only—currency symbols are optional outside the fields. Read the first two lines as cost per one unit of that measure, then check which offer the tool labels as the better buy. If the numbers look odd, confirm you did not mix litres with millilitres or ounces with grams.
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