FLUX 3 Image 5456x3072 at 300 dpi: print size vs Sume pixel caps

A FLUX 3 Image render at the 5456 x 3072 size that Black Forest Labs shows prints about 18.19 x 10.24 inches at 300 dpi, because 5456 / 300 = 18.19 and 3072 / 300 = 10.24. The same image is 16.76 megapixels. A 3840 x 2160 frame, which is the largest 16:9 size that GPT Image 2.5 accepts on Sume, prints 12.8 x 7.2 inches at the same density.

So the print-size question is really a pixel-count question. This page lays out the arithmetic, then says which Sume route to use when you need more pixels than a model returns. FLUX 3 Image itself is not in the Sume image catalog (read 2026-10-07), so the Sume side of the comparison uses the models that are.

What BFL and fal say about FLUX 3 Image output size

The BFL model page says FLUX 3 Image generates in native 2K and 4K, and its largest demonstrated size is 5456 x 3072 pixels (16.8 MP). The fal listing names the resolution tiers 512sq, 768sq, 1k (the default), 2k and 4k, with 4k going up to 16 MP, and warns that higher tiers take longer: 4k can take several minutes.

Neither page promises a fixed pixel size for every aspect ratio. BFL says the exact dimensions depend on the aspect ratio you pick, so the 5456 x 3072 figure is the 16:9 case, not a guarantee for a 1:1 or 3:4 request. Read the width and height from the response before you sell a print size.

Print size at common densities

The table divides pixels by dots per inch. It shows the 16:9 FLUX 3 Image size next to the largest 16:9 size GPT Image 2.5 accepts on Sume. The GPT cap comes from the Sume Image API docs: both edges must be multiples of 16, the longest edge is 3840, the aspect ratio is at most 3:1, and the image has 655,360 to 8,294,400 pixels. 3840 x 2160 is exactly 8,294,400 pixels, so it sits on the ceiling.

How much smaller is the Sume maximum

The 3840 x 2160 ceiling holds 8,294,400 pixels against 16,760,832 for the 5456 x 3072 frame, which is 49.5% of the pixels. Stretch the Sume image to the full 18.19 inch width and the density falls to 211 dpi (3840 / 18.19). That is fine for a poster viewed from a few feet away and soft for a close-up print.

Nano Banana 2.1 and Nano Banana Pro list a 4K tier on Sume, but the docs do not publish exact pixel dimensions for it, so do not assume a number. Read the size of the returned file, then compute the print size from the real width and height.

When you need more pixels than the model returns

Sume has a separate image upscale route. Its catalog price is $0.20 per image, a reserve that assumes about 16 output megapixels (the upscale price explainer walks through it). A 16 MP result is about the size of the FLUX 3 Image frame above, so generate at a size you can afford, then upscale only the images that earn a print.

The cost logic is simple. At the billed price of 0.0375 dollars for a Flux 2 Pro image, a 1,000-image batch is $37.50 before any upscale. Upscaling 50 keepers adds 50 x $0.20 = $10.00. Upscaling all 1,000 would add $200.00, so choose before you batch.

A checklist before you promise a print size

• Ask for the aspect ratio you will print, then read the returned width and height.
• Divide each edge by the dpi your printer needs. 300 is common for books and posters; large banners are often viewed from farther away and accept less.
• If the longest edge is under the pixel count your print needs, plan an upscale step and budget $0.20 per image on Sume.
• Keep the original PNG. Re-encoding to JPEG before the upscale throws away detail the upscaler could have used.