DPI depends on how big you print

The same 3600 pixel wide file is 300 DPI on a 12 inch print and 150 DPI on a 24 inch one. Nothing about the file changed — only the size it was stretched across.

Screens lie about sharpness

Your monitor shows roughly 100 pixels per inch. A file that looks crisp at full screen can be a third of the resolution a printer needs, and you will not see the difference until it arrives.

Upscaling does not add detail

Enlarging a 1000 px file to 3600 px makes the numbers look right while inventing every new pixel. Print it and you get soft edges and mushy text. Start at the final size instead.

Shape matters as much as size

A square design on a 12 x 16 inch print area either gets cropped or floats with empty space around it. Set your canvas to the print area before you design, not after.

What DPI do I need for print on demand?

300 DPI at the final print size is the standard most providers ask for. 150 DPI is the practical floor for large items viewed from a distance, like posters and canvases. Below 150 the print will look soft or pixelated, and no amount of upscaling fixes detail that was never captured.

How do I check the DPI of an image?

DPI is not a property stored in the file in any meaningful way — it depends entirely on how large you print. Divide your pixel width by the print width in inches. A 3600 pixel wide file printed at 12 inches is 300 DPI; the same file printed at 24 inches is only 150 DPI.

Why does my design look pixelated on the printed product?

Almost always because the file was too small for the print area. A 1000 × 1000 px graphic looks fine on screen but printed across a 12 inch t-shirt it is only 83 DPI. Design at the final size from the start rather than scaling up afterwards.

Should I upload PNG or JPG for print on demand?

PNG for anything where the background should not print — apparel, stickers, phone cases. JPG has no transparency, so a white background becomes a printed white box around your design. For full-bleed posters and canvases where the whole area prints, either format works.

What happens if my file is the wrong shape?

The provider either crops it to fit or leaves empty space at the edges, and you rarely get to choose which. Set your canvas to the print area dimensions before you start designing — a 12 × 16 inch t-shirt print area needs a 3:4 file, not a square one.