How many megapixels do you need for a memorial portrait?

The megapixel count sets a limit; it does not settle the question

Give two photographs the same megapixel count and they can still print nothing alike. All the count reports is how many pixels are present, never whether there is anything worth seeing inside them — and a photograph put through a messaging app comes out the same dimensions with the fine texture gone, the texture that lets an eye read as an eye.

Proportions count for as much. Phones frame 4:3 where cameras frame 3:2, so an identical 24 MP file arrives quite differently at an 8x10 than at a 24x36 — the trim happens first, and the resolution is only worked out on what survives it.

When the numbers fall short, the order to try things in is: find the original file, rescan the print at a higher setting, then print smaller. Enlarging comes last, and only with your eyes on the result — it works out what detail probably belonged in the gaps, which is often a real improvement and is occasionally wrong. The figures on this page are never adjusted for it.

Questions

Megapixel questions

How many megapixels do you need for a memorial portrait?

Wholly on the size you are printing. A 5x7 beside the guest book asks for very little; a 16x20 on an easel asks for a great deal. Take the everyday 12 MP phone photograph, 4032x3024 pixels: it stays sharp at 300 DPI as far as A4, and framed it remains acceptable to A3. The megapixel figure on its own can never settle it, because trimming the picture to the frame's proportions discards pixels before anything is printed.

Why does a 48 MP phone save 12 MP photos?

Pixel binning is why. On a high-megapixel phone sensor, neighboring pixels — four of them, or nine — are merged into a single larger one that gathers more light and returns a cleaner picture. What gets written to storage is therefore a quarter or a ninth of the number on the sales page, unless somebody went in and asked for full resolution first. Hence a photograph off a 48, 50 or 108 MP phone usually arriving as a 12 MP file. Recent iPhones are the exception: from the iPhone 15 on, the default is 24 MP.

Does a bigger megapixel number always print better?

At large sizes, and only where everything else is equal — which it seldom is. A 24 MP file that has been squeezed hard can come out worse than a clean 12 MP one, and a phone pushed into full resolution often returns a grainier picture than the merged file it would have written by itself. The count fixes the ceiling; what those pixels actually hold decides how near the ceiling you get.

How do I find out how many megapixels a photo is?

Take the two pixel dimensions, multiply them, then divide by a million: 4032 across by 3024 down comes to 12,192,768 pixels, or 12.2 MP. The quicker route is the free check on this site, which reads the file on your own computer and reports what it prints at. Bear in mind the proportions count for as much as the total — the further a photograph’s shape sits from the frame’s, the more of it the crop removes.

The only photo we have is small. What can we do?

Three things, in order. First, find the original — if it came through a message or off a website it has been shrunk, and the full-size version is usually still on the phone or computer it came from. Second, if it is a paper print, scan it at 600 DPI rather than 300; it costs nothing and doubles what you have. Third, print smaller: a 5x7 or an 8x10 from a small photograph looks far better than a 16x20 does, and a print people can actually see is worth more than a large soft one.