Bleed area (3mm): 426mm x 303mm
The bleed area extends out an extra 3mm from the edge of your finished artwork. All images or colour that print to the edge of your document should be fully extended into this area to avoid the chance of white lines appearing, and ensure that when it’s trimmed your artwork is printed edge to edge. Make sure that you don’t place any important content or artwork elements in this area, as it will get trimmed off.

Trim area: 420mm x 297mm
This is the finished size of your document – anything placed outside of this area will get trimmed off.
Non-Text Area: 414mm x 291mm
Avoid placing any text within 3mm of the edge of the advert and 3mm of the fold as text placed here could possibly be trimmed off or lost in the fold. Avoid using a thin border around the edge of your advert in this area as you will get an inconsistent thickness when trimmed.
Download templates for a double-page spread:

Adobe Indesign
 Adobe Illustrator
 Adobe PDF