Submitting files for large format printing: the checklist

Site signs, banners, scaffold sheets, trade-show stands: with large format printing, your design is often enlarged dozens to hundreds of times over compared to the screen it was made on. What's invisibly small on an A4 sheet suddenly becomes painfully obvious at 3 metres wide. These 5 points help you avoid the most common problems, and save yourself (and us) a back-and-forth of corrections.

For small format print, the rule of thumb is 300 DPI (dots per inch) at full size. For large format printing, that's often neither achievable nor necessary: a file 3 metres wide at 300 DPI would weigh tens of gigabytes. What actually matters is the viewing distance. The further away a print is viewed from, the lower the resolution can be without it being noticeable.

• Trade-show stand, shop window (viewing distance <1 m): 150 to 300 DPI at full size
• Site sign, facade banner (viewing distance 2-5 m): 100 to 150 DPI at full size
• Billboard, large banner (viewing distance >10 m): 20 to 50 DPI is amply sufficient

If your software doesn't run smoothly at full size, work at a reduced scale (e.g. 10 or 25% of the final dimensions) at a higher DPI, and clearly state which scale you worked at. We'll convert it to 100%.

Text and logos should be supplied as a vector file for large format printing (or as text with outlines, so typefaces can't shift). Vector stays perfectly sharp at any size, while a pixel version of the same logo becomes grainy when heavily enlarged. Photos, however, can remain pixel images — the rule of thumb from point 1 applies there. Not sure if your logo is a vector file? We wrote a separate article about it.

The standard 3 mm bleed you know from business cards or flyers isn't enough for large format. How the file will be finished determines how much bleed is needed:

• Banner with eyelets: 2 to 5 cm of bleed all around, to allow for hemming
• Site sign on dibond or corrugated board: 5 to 10 mm is usually enough, unless the sign will be framed
• Design spanning multiple panels or lengths: make sure the pattern lines up seamlessly across the overlap, and clearly indicate the panel order

Your screen displays colours in RGB (built from light), while print work uses CMYK (built from ink). So submit your file in CMYK, not RGB. With large format printing there's an extra factor: the inks and materials (e.g. PVC banner, mesh, dibond) differ from classic offset printing on paper, which can shift colours slightly again compared to your screen. For critical brand colours (e.g. an exact logo blue), it's best to request a sample beforehand.

PDF is the safest choice for large format too: it bundles vectors, pixel images and typefaces into a single file. For purely photographic prints (e.g. a large photo image without text), a high-resolution TIFF also works well.

Large format files are often too big to email. In that case, use a transfer service such as WeTransfer. If your file is smaller than 10MB, it can simply be attached to your quote request. Not sure of the best way to submit a large file, feel free to get in touch: we're happy to offer an alternative.