Across the world, apart from in North America, paper is sold in standard sizes defined by ISO 216. The key feature of these standard sizes being that if you cut a sheet in half parallel to the shortest edge you will get the next size down.

Below are quick lookups for all the A and B paper sizes and C envelope sizes with dimensions in millimetres and inches, conversion between the units is simply a case of selecting the units you need.

A Paper Sizes - Quick Lookup

Select the paper size from the 'Size' selector and the unit from the 'Unit' selector - the dimensions will be shown in the dimensions box.

A paper sizes are the mostly commonly used sizes, with A4 being standard office letter paper.

Click here for a table of all the A paper sizes and more information about their properties.

B Paper Sizes - Quick Lookup

Select the paper size from the 'Size' selector and the unit from the 'Unit' selector - the dimensions will be shown in the dimensions box.

B paper sizes are used when there isn't a suitable A size.

Click here for a table of all the B paper sizes and more information about their properties.

C Envelope Sizes - Quick Lookup

Select the envelope size from the 'Size' selector and the unit from the 'Unit' selector - the dimensions will be shown in the dimensions box.

Envelope size C4 will hold an A4 sheet of paper and is often incorrectly called an A4 envelope.

Click here for a table of all the C envelope sizes and more information about their properties.