Why cutting is never perfect
Printed pieces are rarely printed one at a time at their final size. Printers typically print many copies on a larger sheet and then cut them down with a blade. Paper can shift slightly during printing, stacks can move during cutting, and blades have small tolerances. The result is that the cut line lands within a small range of where it was supposed to, not at an exact spot.
If your design ended exactly at the edge of the page and the cut landed a hair inside it, a thin sliver of unprinted paper would show along that edge. Bleed and safe margins exist to absorb this small variation.
The three zones
Every print layout can be thought of as three nested areas.
Bleed area
Bleed is extra artwork that extends beyond the intended edge of the finished piece. If a background color, photograph or pattern is meant to run right to the edge, it needs to continue into the bleed. A common request from print shops in the United States is about one eighth of an inch (0.125 inch) on each side, but requirements vary, so check with your shop. Metric-based shops often ask for around 3 millimeters.
The bleed is cut away and discarded. Its only job is to make sure that, even if the blade lands slightly outside the trim line, there is still ink to the edge.
Trim line
The trim line marks where the piece is intended to be cut. It represents the finished size. If you are designing a business card of 3.5 by 2 inches, the trim line sits at exactly those dimensions.
Safe area
The safe area, sometimes called the safety margin, is an inner boundary. Text, logos and other important elements should stay inside it. If the blade drifts slightly inward, nothing essential will be clipped, and the content will not look cramped against the edge. Many shops suggest something like one eighth to one quarter inch inside the trim line, though a larger margin can look more comfortable, particularly on small pieces.
A worked example
Suppose you are designing a US letter flyer, which is 8.5 by 11 inches, with a full-color background and a bleed of 0.125 inch.
- Finished (trim) size: 8.5 by 11 inches.
- Bleed adds 0.125 inch on every side, so width becomes 8.5 + 0.125 + 0.125 = 8.75 inches, and height becomes 11 + 0.125 + 0.125 = 11.25 inches.
- Your document with bleed is therefore 8.75 by 11.25 inches.
- If the safe margin is 0.25 inch inside the trim, text should stay within a box of 8 by 10.5 inches (8.5 minus 0.5, and 11 minus 0.5).
Those numbers are only an example. Always use the figures the print shop provides.
What needs to extend into the bleed
Only elements that touch the edge need bleed. Examples include:
- Background colors and tints.
- Photographs meant to fill the page.
- Borders or bars that run off the edge.
- Patterns and textures that continue past the trim.
Extend these elements all the way to the outer bleed boundary rather than just to the trim line. A photograph that stops at the trim line has no safety buffer, which defeats the purpose. If an image is not large enough to reach the bleed edge, you may need to enlarge or reposition it, taking care that its image resolution still holds up at the larger size.
Common mistakes
- No bleed at all. Files that end at the trim line often produce thin white edges on some copies. Many shops will reject such files or ask for corrections.
- Bleed that only partly extends. An edge-to-edge color band that runs to the trim but not past it leaves the same risk.
- Text too close to the edge. A layout may look fine on screen but feel tight, or even get clipped, after cutting.
- Confusing margins with safe area. Page margins in a layout grid are a design decision about composition; the safe area is a production boundary. Often they are different, and layout grids can sit comfortably inside the safe zone.
- Borders placed near the trim. A thin frame drawn just inside the edge is especially risky, because slight cutting variation makes the border look uneven, thicker on one side than the other. Either place it with generous space inside the trim or skip a border that depends on exact alignment.
Bleed with folds, boxes and bound pieces
On folded items, the fold position is also subject to small variation, so elements that must line up across a fold need extra care. For bound books and booklets, pages near the spine can lose some visible area into the binding, so keep important content further from the inner edge. Packaging and die-cut items such as boxes use a template supplied by the manufacturer that already marks bleed, folds and cut lines, and it is best to build directly on that template. Some of the choices involved in packaging design depend heavily on following such templates.
Marks and settings
Print-ready files may include crop marks, small lines placed outside the trim area to show where the cut should happen. Some shops want them, and others prefer none because they add their own. Your software typically offers settings for bleed and crop marks at export. Whether to include them is another detail to confirm with the shop.
Keep in mind that crop marks must sit outside the bleed, not inside it, or they could end up in the printed area.
A quick checklist
- Ask the shop for its bleed and safe margin requirements.
- Set up the document at the finished size and add the bleed.
- Extend edge-touching artwork past the trim line, to the bleed boundary.
- Keep text and logos inside the safe area.
- Check fold lines, spines and die-cut templates if they apply.
- Review the exported file to make sure bleed appears as expected.
Once the idea is familiar, setting up bleed takes only moments. It is a small step that protects a printed piece from one of the most visible, and most avoidable, kinds of error. Leaving enough white space near edges also makes a design more forgiving.