Most print problems are file problems, and most file problems are caught either by a good prepress operator or by the customer opening a delivery and discovering the logo is fuzzy. This is a practical guide to preparing artwork for large-format printing — banners, wall graphics, stickers, canvas, exhibition displays — written for people who design their own materials in-house without a prepress background.
Resolution: the rule nobody explains properly
The advice “always use 300 dpi” comes from magazine printing, where pages are read at 30 cm. It is actively unhelpful for large format, where it produces enormous files for no visible benefit.
What actually governs required resolution is viewing distance. The human eye resolves roughly one arcminute of detail, which translates to a simple working table:
- Viewed at 0.3 m (stickers, small labels, close-viewed panels): 250-300 dpi at final size.
- Viewed at 1 m (exhibition graphics, indoor posters): 150 dpi.
- Viewed at 2-3 m (roll-up stands, shop-window graphics): 100-150 dpi.
- Viewed at 5 m (wall banners, building signage): 50-72 dpi.
- Viewed at 20 m+ (billboards, façade wraps): 20-30 dpi.
A 4 × 2 metre banner at 30 dpi requires a 4724 × 2362 pixel image — entirely achievable from a decent camera. The same banner at 300 dpi would need 47,244 × 23,622 pixels, a file of several gigabytes that would look identical from the pavement.
The practical technique is scale design: build the document at 1:10 (a 4 × 2 m banner as a 400 × 200 mm file) at 300 dpi, which yields 30 dpi at full size. Everything stays manageable and the printer scales up at output.
Vector versus raster, and why it matters at size
Raster images — photographs, anything from a camera or a screenshot — are grids of pixels and degrade when enlarged. Vector artwork — logos, type, shapes drawn in Illustrator, Inkscape or Affinity Designer — is a set of mathematical paths and is resolution-independent, printing perfectly at any size.
The consequence is a firm rule: logos and text must be vector. A logo lifted from a website is typically 300 pixels wide; enlarged to 60 cm on a banner it will be visibly soft, and no amount of sharpening fixes it. Ask whoever designed your identity for the original AI, EPS, SVG or PDF file, and keep it somewhere findable. It is the single most valuable asset in a small company’s brand folder.
Convert type to outlines (or embed fonts) before sending. Missing fonts are the most common single cause of a job being sent back, and font substitution that goes unnoticed produces a print with the wrong typeface.
Colour: RGB, CMYK, and why the screen lies
Your monitor emits light and mixes red, green and blue. A printer lays down cyan, magenta, yellow and black ink that reflects light. The two gamuts overlap but are not the same shape, and some vivid RGB colours — electric blues, neon greens, bright oranges — simply cannot be reproduced in CMYK ink. They will print duller, and this is physics rather than a printer’s failing.
Practical guidance differs by product, which surprises people:
For solvent and UV large-format work (banners, vinyl, rigid boards), convert to CMYK yourself before sending, using a profile your printer specifies if they offer one. This gives you the chance to see and correct the shift rather than discovering it on the finished print.
For photographic products on wide-gamut media (canvas, fine-art paper, photo prints), do the opposite: send RGB with the profile embedded and let the printer’s RIP convert. Modern inkjet systems have a gamut wider than generic CMYK in several regions, and converting early throws away colour you could have kept.
Where brand colours matter, supply Pantone references alongside the file. A printer can target a Pantone far more accurately than they can guess what “our corporate blue” should be. Be aware that not every Pantone is achievable in CMYK — ask for a proof if a specific colour is critical.
Two further colour notes. Build rich black for large solid areas — pure 100% K prints as a washed-out dark grey at size; something like C60 M40 Y40 K100 gives a genuinely deep black. And avoid total ink coverage above roughly 300% on any substrate, since excessive ink does not dry properly and can cause bleeding or offsetting.
Bleed, safe zones and trim
Cutting has a tolerance of a millimetre or two, and finishing consumes edge area.
Bleed is background extended beyond the final trim line so that a slightly off cut does not reveal white paper. Small items: 3 mm. Large-format: 10-20 mm at final size. For banners with hems, extend further — the hem folds material away, so ask your supplier how much.
Safe zone is the margin inside the trim within which no important content sits. Small items: 3-5 mm. Large-format: 20-50 mm. For roll-up stands the bottom safe zone is far larger, since the base housing and the crowd hide the lower portion entirely.
Grommet allowance: keep critical content at least 5 cm from edges on any banner that will be eyeleted.
File formats and delivery
PDF/X-4 is the correct delivery format for almost all commercial print. It embeds fonts, preserves transparency and vectors, and carries colour profiles. Export with bleed and, where the printer asks for them, crop marks.
TIFF is fine for pure photographic work with no type — canvas prints, photo panels.
Native files (INDD, AI, PSD) only if the printer explicitly requests them, and then package all linked images and fonts.
Avoid: JPEG for anything containing text (compression artefacts appear as fringing around letters), Word or PowerPoint files (no colour management, no bleed, unpredictable font handling), and images pulled from a website (low resolution, RGB, often compressed several times over).
Name files clearly and unambiguously — “Company_Banner_3000x1000mm_v3_FINAL.pdf” tells a prepress operator everything, and “final2.pdf” tells them nothing. Include the finished size in the filename; it is the single most useful habit in the whole list.
The checks worth doing before you send
- Zoom to 100% at final size and inspect the lowest-resolution image in the file. If it is soft on screen at that magnification, it will be soft in print.
- Confirm every logo is vector, not a placed PNG.
- Outline or embed all fonts.
- Check the colour mode matches the product — CMYK for solvent/UV work, RGB with profile for photographic media.
- Verify bleed and safe zone against the actual finished size, not the design size.
- Check document dimensions in millimetres. Confusing a 1:10 scale document with a full-size one is a classic and expensive error.
- Read the text out loud. Typos in 10 cm letters are memorable in the wrong way, and spellcheck does not catch a correctly spelled wrong word.
- Confirm the phone number and web address character by character. This is worth doing separately from proofreading the rest.
Proofs
For anything large, expensive or colour-critical, ask for a proof. A soft proof (a PDF with the printer’s profile applied) is free and catches layout errors. A hard proof — a small printed section on the actual material — is the only reliable way to judge colour, and on a large order it costs very little relative to the risk. Any print shop that resists supplying one on a significant job is telling you something. Producers who handle both design and production, such as Printobella, will usually run a proof section as a matter of course on large work.
When to hand it over
There is a reasonable case for not doing this yourself. If the artwork carries a brand you intend to use for years, if it involves a complex substrate, or if you do not have the original vector logo, the design fee at a print studio is usually a fraction of the cost of reprinting. The useful skill for a non-designer is not producing print-ready files; it is knowing enough to brief properly and to spot a problem before it goes on the machine. The studio’s site sets out what they need from a client file, and reading a supplier’s file requirements before starting a design saves more time than any other single step.
Summary
- Resolution follows viewing distance — 30 dpi at full size is fine for a wall banner, 300 for a sticker.
- Design large-format at 1:10 or 1:4 scale to keep files manageable.
- Logos and text must be vector; outline or embed fonts.
- CMYK for solvent/UV work, RGB with embedded profile for canvas and photographic media; supply Pantone references.
- Build rich black for large solid areas; keep total ink under ~300%.
- 10-20 mm bleed and a generous safe zone at large sizes; more for hemmed or eyeleted banners.
- Deliver PDF/X-4, named with the finished size, and ask for a proof on anything significant.
