- What are crop marks (trim marks) in a PDF?
- Crop marks — also called trim marks or cut marks — are thin lines drawn just outside the intended final size of a printed page. They tell the print shop's guillotine or die-cutter exactly where to trim the paper after printing, ensuring the finished piece is the correct size. Without crop marks, operators must guess where to cut, leading to misaligned or inconsistent results.
- What is bleed and why do I need it?
- Bleed is a border of artwork that extends beyond the final trim edge — usually 3 mm on all sides. Because cutting machines have a small mechanical tolerance, any design element that should reach the very edge of the page (a background colour, a full-bleed photo) must extend into the bleed zone. If it doesn't, a white sliver of paper may appear at the edge after cutting. This tool expands your page canvas by the bleed amount, giving your artwork room to bleed, and then draws crop marks so the trimmer knows the final size.
- What bleed size should I use?
- 3 mm (approximately ⅛ inch) is the global standard for most commercial print work — business cards, flyers, brochures, and book covers. Some large-format printers require 5 mm. Packaging and folding cartons may specify up to 5–10 mm. When in doubt, check with your printer; 3 mm is a safe default for almost every offset and digital press job.
- What is the "mark offset" setting?
- The mark offset is the gap between the outer edge of the bleed area and the starting point of each crop mark line. A typical offset is 3 mm. This gap ensures the marks themselves don't overlap the bleed artwork and remain clearly visible as cut guides. The mark then extends outward for the "mark length" (default 7 mm), giving the operator a clear visual target.
- Does this tool modify the original content of my PDF?
- No. This tool only expands the media box (the canvas) and draws new vector lines at the corners. The existing page content — text, images, vector art — is untouched and repositioned to account for the added bleed margin. The crop marks are drawn as thin black lines outside the original content area. Your original file is never sent to a server; everything runs locally in your browser using the pdf-lib JavaScript library.
- My PDF already has a bleed — will this double it?
- If your PDF was exported from design software with bleed already included (i.e., the file is already larger than the trim size), you should set the bleed width to 0 and only add the crop marks. Use the bleed width field to add additional canvas, not to re-specify existing bleed. If you are unsure, check your PDF dimensions against the intended trim size first.
- Does it work with multi-page PDFs?
- Yes. Crop marks and bleed are added to every page in the document. Each page is processed individually, so mixed page sizes (for example, a document with both A4 and A5 pages) are handled correctly — the canvas expansion is calculated per page.