Scale and viewing distance
An element viewed from 30 centimeters needs a very different level of detail than one viewed from 5 or 10 meters away, as is often the case with banners, signage and trade show displays. For more on how effective resolution is calculated based on size and distance, see the dedicated guide on blurry printed images: the same principles apply, but with much wider margins in large format.
Effective resolution, not the working file's resolution
Many large-format files are designed at a reduced scale (for example 1:10) and then enlarged by the printer's system at print time. In these cases, what matters is the real resolution at the final print size, not the one read in the file at the working scale: a file that looks high-resolution at a reduced scale can turn out insufficient once brought back to the real size.
The substrate changes how color renders
Vinyl, fabric, mesh, rigid panels: every substrate absorbs and reflects light differently, with a real impact on perceived color. A generic color profile doesn't account for the specific combination of substrate, ink and printer used — for a deeper look at how color profiles work, see the guide on screen vs. print color; in large format, the correct profile needs to be confirmed for the specific material combination.
Bleed in large format: not the same value as small-format print
The bleed needed in large format depends on the application method: a rigid panel, a banner with grommets, an installation wrapped around a frame all have different requirements. The roughly 3mm figure given for small-format commercial print (see the dedicated bleed guide) doesn't automatically apply to large format, where a much wider margin is often needed.
Panelization and seams
Very large prints are often split into multiple panels for technical reasons (maximum printer width, transport, installation). This split needs to be planned directly in the file, with overlap margins and alignment references — it can't be improvised after the file is already finished.
Manufacturer specs always need confirming
Every large-format print supplier has its own technical specs: maximum file size, required color mode, minimum accepted resolution, panel size, safety margins. There's no single standard that fits every supplier: the specs always need to be confirmed before finalizing the file, never assumed.
Common mistakes to avoid
Applying desktop-print resolution rules without considering the real viewing distance. Ignoring how the specific substrate alters color rendering. Forgetting the overlap needed on a panelized job. Assuming the standard 3mm bleed is enough for large format too.