1aWhat is Bleed?

Bleed is the area (usually 3mm) added to all four edges of a page. The purpose of bleed is to eliminate any chance of a white (unprinted line) at the edge of the document after it has been trimmed.

An A4 document has a finished size of 210mm x 297mm. With 3mm bleed it will measure 216mm x 303mm. (see figure 1) 3mm extra added to the top and bottom, and left and right of the document adds 6mm overall to both the height and width. The same applies to any page size and will always require 3mm bleed as standard to each of the edges original dimensions. So a business card 55mm x 90mm with bleed added would be 61mm x 96mm. The finished document will still end up the correct size as the bleed area is trimmed off.

Why do we need bleed?

We do not trim your printing one sheet at a time. It is trimmed in stacks on a guillotine. Due to the slight differences in the position of the printing on each sheet the edge of the printing is in a slightly different position on each sheet in the stack. The guillotine operator can only see the edge of the top sheet. If they line the blade up to cut exactly on the edge of the artwork on the top sheet it will inevitably be slightly out on other sheets in the stack. This is a problem as it will leave a thin white lie on two edges of any miss aligned sheets. To overcome this printers use bleed and crop marks. The bleed is the 3mm extra image that is printed past the intended edge of the final document. The guillotine operator lines their blade up on the crop marks, not on the edge of the image. They then cut off the extra 3mm of image leaving a finished image the correct size with no white borders.

Any element of your design that touches any trim edge needs to extend 3mm over the edge of the finished page size. While this is easy for solid background colours it can be tricky when using photographic images. If your photo is A5 and you are designing an A5 document you will need to increase the size of the image so that it is 3mm bigger in all directions. All 4 edges will then be trimmed off; this can cause problems with some images so it is import to consider this when selecting a photo to use. Make sure there is nothing important on the edge of the photo that will be trimmed off. (see figure 2)