24x36 poster from Nano Banana 2.1 at 4K: 3392x5056, about 140 dpi

A 24x36 inch poster made from a Nano Banana 2.1 image at 4K and 2:3 has about 140 pixels per inch, because Google's size table lists that output as 3392 by 5056 pixels. Sume bills the 4K tier at $0.20 per image. At 140 dpi a poster is fine from a few feet away and soft from close up, so it suits wall art viewed from across a room.

Print shops usually ask for 150 to 300 dpi, so check your shop's minimum before you order. This page gives the numbers, not a quality verdict.

Pixels per inch for five print sizes

The sizes come from the 4K column of the Nano Banana 2.1 table on Google's image generation page (read 2026-10-09), matched to the nearest listed ratio. Pixels per inch is the pixel width divided by the print width, and the pixel height divided by the print height.

How to read the table

The ratio must match the print, or you lose part of the image to a crop. 24x36 and 20x30 are both 2:3, so both fit exactly. A 16x20 print is 4:5 and also fits exactly. At 12x12 inches the square 4096 pixel render gives about 341 dpi, which is above what most shops ask for.

The larger the print, the lower the dpi. The same file prints at about 141 dpi at 24 inches wide and about 170 dpi at 20 inches wide, since 3392 divided by 20 is 169.6.

Choosing the print size

If you only have one render, pick the print size from the table above rather than the other way around. A 16x20 inch print at 4:5 gives about 232 dpi across, which is the sharpest of the larger sizes here, and a 12x12 inch square gives about 341. The larger the wall space, the more you give up in sharpness, and you should decide how close people will stand to it.

Frame and viewing distance matter as much as the number. A poster behind glass in a hallway reads differently from a print on a desk. Order one small proof of the actual file before you order ten large ones.

Getting past the ceiling

To reach 300 dpi at 24x36 you would need 7,200 by 10,800 pixels, or 77.76 megapixels. Sume's image upscale reserves about 16 megapixels of output at the flat $0.20, per the catalog, so a target that size is outside what that $0.20 price is built for. Reduce the print size, accept a lower dpi, or check what output size the upscale returns on a test file before you plan around it.

Sume lists the 4K tier for Nano Banana 2.1 and the 2:3, 3:4, 4:5 and 1:1 ratios. The Sume docs do not state returned pixel sizes, so open the file you receive and read its width and height. The Image API docs describe how to pass resolution and aspect_ratio.

A 4K request is one of the slow configurations that can answer with a 202 job envelope. Poll the job status endpoint and fetch the result when it is done.