How to Prepare
Print-Ready Files.

Trim, bleed and safe margin - three different lines

Every printed piece has a trim line — where the sheet is cut to its finished size. As standard prepress convention, anything meant to run to the edge of the piece needs to extend at least 1/8″ past that trim line, called bleed. Sheets are cut in stacks, and even a well-set cutter moves by a hair from sheet to sheet; bleed is the margin that absorbs that hair so the edge never shows an unprinted white sliver. The opposite margin matters too: keep type and anything else you cannot lose at least 1/8″ inside the trim line, for the same reason in the other direction.

Resolution: ppi is not the same question as dpi

These two get used interchangeably and they are not quite the same measurement. PPI (pixels per inch) describes how much image data a digital file actually contains. DPI (dots per inch) describes how finely a specific output device — a platesetter, an inkjet printer — can lay down marks. A file’s ppi is fixed the moment it is created or scanned; a device’s dpi is a property of the hardware. As a standard convention, photographs should be supplied at 300 ppi at the size they will actually print, and fine line art or scanned type at up to 1200 ppi. An image pulled off a web page is usually around 72 ppi at screen size — sharpening or enlarging it afterward cannot add detail the file never captured, it can only make the existing pixels bigger.

Vector vs. raster

A logo or type set as vector art (built from mathematical paths, as in Illustrator or a PDF export of one) can scale to any size with no loss of sharpness, because there are no pixels to run out of. A raster image — a photograph, a scan — is a fixed grid of pixels and can only be reproduced at its native resolution or smaller. Sending a raster logo when a vector version exists is one of the most common ways a good-looking file becomes a blurry printed piece.

Color space, briefly

Files built for print should be in CMYK, not RGB — the difference, and why a screen never quite matches a printed sheet, is worth its own explanation; see CMYK vs. RGB. If a spot color needs to hold exactly, name it by its Pantone number rather than as a CMYK approximation, so it is set up to print as its own solid ink instead of being simulated from four dot screens — see spot color vs. process color.

Fonts and export

A font merely installed on your computer is not, by itself, part of the file. Embed the fonts in the exported PDF, or convert the type to outlines, so nothing depends on the receiving computer happening to have the same font. For export, a press-ready PDF built to the PDF/X-1a or PDF/X-4 standard removes most of the guesswork: both presets force embedded fonts and a defined color space, and X-4 additionally carries live transparency rather than flattening it on export.

Two things worth checking before you hit send

The bleed & trim size calculator turns a trim size and a bleed amount into the actual file setup size and the safe margin, so the numbers do not have to be worked out by hand. The image resolution checker takes an image’s pixel dimensions and the size you plan to print it at and tells you whether it clears 300 ppi. Running a file through both catches the two most common rejection reasons in one pass.