Packets and containers of food and other items are sold in different sizes. If you want to compare the
prices of the same item in different-sized containers, it
is helpful to be able to work out a unit price.
This means the price of one gram or one litre, or
any other suitable unit.
Here are two packets of rice.
Which is better value?
You could find the cost/gram of rice from each packet.
For the smaller packet:
£0.89 200-£0.004 45 per gram
or 89+200-0.445p/g (pence per gram).
For the larger packet:
£2.09 500 £0.004 18 per gram
or 209 500 0.418p per gram.
The larger packet is better value because it costs less per gram.

​