What resolution does a photo need to be printed?

Every print is composited at 300 dots per inch. A source that cannot reach that floor at the size requested is refused rather than printed soft and posted anyway.

That check is ours. It is worth knowing it exists, because the printing side imposes no minimum of its own — without it, a too-small file would simply be stretched.

What 300 dpi actually means for a file

At 300 dots per inch, a 12 by 12 inch print wants roughly 3,600 by 3,600 pixels. A 16 by 20 wants about 4,800 by 6,000. A 20 by 28 wants around 6,000 by 8,400.

Those are large numbers and most phone photographs from the last decade clear the first comfortably. Scans of small old prints frequently do not clear any of them, which is the case worth planning around.

Megapixels are the wrong unit

A file's pixel count describes how many pixels there are, not how much of the photograph is in them. A 1970s print photographed on a phone produces a large file full of soft edges, scanner grain and colour drift.

The file is big. The photograph is not. What matters is how much genuine detail survives — the edge of a coat, the lettering on a sign, the line of a jaw.

Why refusing is better than printing

A soft print does not look like a soft file. It looks like a mistake somebody made, and it is the kind of thing that gets noticed the moment it is unwrapped and never stops being noticeable afterwards.

Declining the size and offering a smaller one is a worse conversation to have before an order and a much better outcome after it.

What to do if your photograph falls short

Buy the size it supports rather than the size you wanted. A small print that is sharp reads as a deliberate choice; a large one that is soft reads as a failure.

The related limits — where enlargement stops recovering and starts guessing — are in how far can a photograph be enlarged, and the practical sizing question is in how big can you print an old photograph.