Print Preflight Checklist

Six checks in a fixed order — geometry, resolution, color, ink, type and proofing — each one mapped to the rejection it prevents at the printer.

Preflight exists because of where faults are cheapest. A missing bleed or an unembedded font found while the file is still open costs a few minutes; the same fault found after plating stops the press and turns into a reprint. The checks below run in order because the early ones set the geometry the later ones are measured against.

Steps one and two are geometry. Set the page to the final trim size, then extend full-bleed artwork 3 mm (0.125 in) past every edge — its absence triggers a 'missing bleed' rejection. Then pull text, logos and page numbers at least 5 mm inside the trim line, into the safe margin, out of reach of the cut.

Step three is resolution. For every placed image, divide its pixel dimensions by its placed size in inches: the result must reach 300 DPI for commercial print, or 150-200 DPI for large-format posters. Anything short triggers a 'low-resolution images' rejection, and no press can add the missing detail back.

Step four is color and ink. Convert the file to CMYK — an RGB file is rejected or converted blindly — and check total ink coverage against the 260-300% cap, because past the cap the sheet cannot dry. Saturated blues deserve a second look at this stage; the reason is explained on the RGB vs CMYK Color Modes page.

Step five is type and linework. Embed every font or convert it to outlines — 'fonts not embedded' is among the most common rejections — and thicken any rule thinner than 0.25 pt, which can drop out on press entirely. Step six is proofing: export the press-ready PDF and judge the proof under D50 (5000 K) light, not beside a 6500 K window and not under 2700-3000 K office bulbs. The numbers behind each step are on the homepage; container choice is on the Print File Formats page.

• 1. Trim size set, 3 mm bleed on every edge — avoids 'missing bleed'
• 2. Text and logos 5 mm inside trim — avoids 'content too close to trim'
• 3. Effective DPI at 300 (150-200 large format) — avoids 'low-resolution images'
• 4. CMYK conversion, ink coverage under 260-300% — avoids 'ink limit exceeded'
• 5. Fonts embedded or outlined, hairlines at 0.25 pt minimum — avoids 'fonts not embedded'
• 6. Proof judged under D50 (5000 K) — avoids color disputes at approval

Further reading

• RGB vs CMYK Color Modes
• Print File Formats: PDF, AI, EPS, PNG, JPEG