Unit Price Calculator

1. 1Enter each option's price and the size of one pack, and choose its unit.
2. 2For multipacks, enter the number of packs included in the price.
3. 3Add more options if you are comparing several sizes.
4. 4Choose the unit to compare by, such as per 100 g or per litre, and read which is cheapest.

Each option is converted to a base unit — grams, millilitres or items — using exact definitions such as 1 lb = 453.59237 g and 1 US fl oz = 29.5735 ml. The unit price is the price divided by the total amount: size of one pack × number of packs.

The cheapest option is the one with the lowest price per base unit. The others show how much more they cost per unit as a percentage, so 0.36 against 0.30 per 100 g is 20% more.

Weight and volume cannot be compared without knowing the product's density, so options measured differently from the first option are left out of the comparison rather than guessed.

Small unit prices are shown with up to four decimal places, because two decimals can make different prices look the same. Everything is calculated in your browser.

1.5 kg for 4.50, 500 g for 1.80, or four 250 g packs for 5.00

1. 4.50 ÷ 1500 g × 100 = 0.30 per 100 g
2. 1.80 ÷ 500 g × 100 = 0.36 per 100 g
3. 5.00 ÷ (4 × 250 g) × 100 = 0.50 per 100 g

Result: The 1.5 kg bag is cheapest; the 500 g bag costs 20% more per gram and the multipack 67% more.

• Only compare unit prices for things you will actually use before they spoil.
• Compare per 100 g for small items and per kg or per litre for bulk.
• Check drained weight for tinned food; the label's net weight includes the liquid.
• Factor in a voucher or loyalty discount by entering the price you will actually pay.