Is your image big enough for that wall?

Ask what resolution a mural needs and you will usually be told 300 DPI, which is the correct answer for something held in your hands and a wasteful one for something on a wall. The variable that actually decides it is viewing distance. Published large-format guidance is consistent on this: roughly 300 PPI for handheld viewing, around 200 to 240 for wall art seen at two to three feet, and 100 to 150 for large pieces seen from four to six feet.

The reason is simply that human vision has limits. A poster viewed from six feet cannot be told apart at 150 PPI versus 300 — the extra detail is genuinely invisible, and insisting on it means a file four times larger for no visible gain. This matters at wall scale more than anywhere else, because a demand for 300 PPI across twelve feet produces a file that is difficult to produce, slow to handle and no better to look at.

So the tool asks how far away people will stand, and grades against that. Where a file is close but not quite there it says marginal rather than failing it, because marginal is often perfectly acceptable and worth a conversation rather than an automatic rejection.

If your artwork is a logo, lettering, a diagram or an illustration built from shapes, the entire resolution question falls away. Vector files describe geometry rather than pixels, so they scale to any size with no loss whatsoever. A vector logo works identically on a business card and on a twelve-foot wall.

This is particularly relevant to script and calligraphic work. Setting Gurmukhi, Devanagari, Urdu, Arabic, Hebrew or any other script at architectural scale should always start from live text converted to clean vector outlines, never from a photograph or screenshot of the text. Conjuncts and ligatures that read perfectly at body size can collide or break apart when they are metres tall, and that is a problem to solve in the outlines rather than in the pixels.

The practical implication: if you are commissioning artwork and it could plausibly be built as vector, ask for it that way. It removes an entire category of problem before it exists.

A shortfall is not automatically fatal. The first question is whether the viewing distance you selected is genuinely right — people often pick a stricter one than the room warrants, and a hall wall really is seen from across a room. Re-running with an honest distance sometimes resolves it entirely.

If it is genuinely short, the tool gives you the pixel dimensions you would need. That number is worth having, because "send me a bigger file" is an unhelpful request and "I need at least 7,200 by 4,800 pixels" is one a photographer or stock library can act on immediately. If the image came from a camera, the original raw or full-size export is frequently several times larger than whatever has been passed around by email.

What does not work is upscaling a small file and hoping. Enlargement software can invent plausible detail, but at wall scale, across a surface someone will stand in front of for years, invented detail tends to look exactly like what it is. It is better to change the image, change the crop, or change the composition to suit what you actually have.