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Everyday Calculators

Unit price comparison

Which pack size is actually cheaper.

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e.g. litre, kg, 100 g, item

Option A

Price per litre
$17.90

Option B

Best value
Price per litre
$16.60

Option C

Price per litre
—

Cheapest per unit

$16.60

Option B — per litre

How it works

Supermarket shelves make comparison deliberately hard. Enter the price and size of up to three options and the cheapest per unit is highlighted.

Unit price = Price ÷ Quantity

Example: 1.5 litres for 24.90 beats 1 litre for 17.90 — 16.60 per litre against 17.90.

Questions people ask

Do the units have to match?

Yes. Convert everything to the same unit first — all grams or all kilograms — or the comparison is meaningless.

Is the bigger pack always cheaper?

No. Multi-buys and promotions regularly make the small pack cheaper per unit, which is exactly what this catches.

Should I always buy the cheapest per unit?

Only if you will use it. A cheaper unit price on food you throw away is the most expensive option there is.

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