How to describe Pie Chart

i)Do I have to include all of the information in a pie chart?
No, you don't. Pie charts often have categories such as 'miscellaneous' and 'others'; you don't have to include these areas in your answers because it's not really clear what they refer to and they are normally included just to make up 100%.

ii) If there's only 1 pie chart?
It's probably best to look for 2 or 3 groups within the chart, for example: small / medium / large. Take a look at the chart below:

In this chart you can put BMW and Benz into the 'small' group, Toyota and Honda into the 'medium' group and Nissan and Mitsubishi into the 'large' group.

iii) If there are 2 pie charts?
If there are 2 charts that are related, then you should compare them. Look at the example below:

Here, you can compare between car makes that increased (BMW and Honda), the ones that decreased (Mitsubishi and Nissan) and those that remained stable (Benz and Toyota).

If you get 2 pie charts that are not related, deal with them separately in 2 paragraphs - don't try to compare or you could get into a mess.

Problems: Some people only repeat the percentage for each category and so don't show a variety of vocabulary.

You could write: "The great majority of sales were of Moschino bags at 82%, whereas Gucci sales accounted for only 18%."

You could write: "The majority of dishes sold were Kow Pad Moo at around one-third of all sales. Kow Pad Goong and Kow Pad Gai accounted for just over and just under one-quarter of sales respectively. Finally, only a few dishes of Kow Pad American were sold."

Useful language:
a few a small/large proportion of
a fair amount of
the (vast/great) majority of
one quarter
(around/about) one-third
(just under/over) a half three-quarters