A flyer may appear well-centered to you on your desktop, but when it comes out of the printer, you might find that the edges are slightly uneven with a white border of paper, and your text is uncomfortably close to the edge. This may not necessarily be a design flaw; rather, it is likely a problem caused by not setting the bleed, trim, and safe-area boundaries correctly.
The Trim Line is the line that defines the final dimensions of your document once it’s been cut to the size intended. So if you are laying out a business card that needs to come out at 90 x 50 mm, then that’s the dimensions of the Trim Size. A print shop will run a larger size and then trim it to the desired size afterwards. Cutting machines can vary in accuracy but even the best cutters can have a slight variation in cuts. Therefore backgrounds need to run slightly beyond the Trim Line and important content should not run too close to the cut edge.
Bleed is a section of image or background that falls outside the Trim Area. A flyer with background that should go right to the edge of the page will require an extension of that colored background past the final trimmed size. Then when your image is cut it won’t look like an unprinted strip of paper. How much bleed you should have should be set out by the printers so you should confirm this before you start laying out your file. It’s normal to have the same amount of bleed on all four sides of your document, but you should check that with the printer as sometimes it won’t be the same, or you’ll be doing a run which requires a slightly different bleed.
The Safe area is where the area inside the Trim Size defines a boundary for content to keep away from the cutting edges. Things like text, images, logos, page numbers and other items should be positioned within the Safe Area. Items placed between the safe-area boundary and the trim line are at risk of being partially cut off or appearing crowded once printed. Background colors and full-bleed images can extend past the safe area, but key text and logos must remain within the boundaries. The amount of area for this will vary depending on the print medium (for example, if you have a folded document with a binding, it could make a difference).
It may be useful to put the safe area and trim line and bleed boundaries on the same document just so you can see how they interact. You can make a test document for a simple item like a business card. Set it up to the correct size and bleed dimensions, and create temporary lines to define the safe area. Create a colored background and make sure it goes beyond the Trim Line and the edge of the Safe area. Place all your text (such as your company name, telephone number, email, and other logos and information) inside the Safe Area. Create your PDF and then look at the final PDF and zoom right in and see if your background goes beyond the Trim Line and that all your text is within the Safe Area and not too close to the Trim Line. Remove the lines and safe areas that you’ve created before sending the final PDF to print.
This will also help to make some common file problems clear. If you look at a photo and it seems as if it stops abruptly before the image edge, then you’ll need to change the size of the image or move it over so it falls beyond the Trim Line. If a logo seems to be sitting on the edge of the Safe Area or the Trim line then you’ll need to move it inside a safe distance. A line border that seems too close to the edge is a common problem in printed files where the cut seems to be off. Just because it looks fine on your PDF layout file doesn’t mean you have a safe file for printing, as some files are laid out at the exact size required for printing. With folded brochures this can be especially relevant as it adds an extra area to be careful of where the text and other elements will run into the fold line making it harder to read.
So before you submit a file for printing take a moment to look at your document as three distinct areas; the Bleed is to protect against the cut falling just outside the edge and missing the image, the Trim Area is to ensure the document ends at the correct dimensions, and the Safe Area is to ensure that all essential information is clear of the cut line. Confirm any size details with your printer, check the final PDF and don’t rely on the design file alone. If you are looking at a PDF you can imagine that the line is not in exactly the center position and still be confident the layout will look great.