DPI vs PPI

[Wallahoopi]

Have a printer requesting 8.5"x11", 300 dpi, 1/8" bleed.

Have a GIMP doc at 2625x3375 and 300 ppi. Printer says it's coming up as wrong size and 72 dpi. 

Am I missing something or are ppi and dpi not comparable?

[rich2005]

Strictly, an inkjet printer spits ink out at a DPI rate which might much greater than your document PPI. 600 dpi might be low quality, 2400 dpi might be high quality. Your printer software can set quality.

When it comes to creating a document, it is pixels-per-inch PPI Each pixel created by the printer spiting out the appropriate mix of tiny ink droplets according to quality.

PPI is correct but DPI is often used in its place. Do not worry about it.

Your 2625x3375 @ 300 ppi = 8.75 x 11.25 inches, that size includes the bleed margin.

In Gimp go to Image -> Print Size and that is what it should report. Exporting as a jpeg or a tif should keep that 300 ppi in the file meta-data which is used by the printer. An exception to this is using PDF format which just keeps the page size.

Generally 8.75 x 11.25 will never print on a home printer, a USletter size 8.5 x 11 is imposed, extra margins might be added and the image shrinks to fit the paper.

If you are sending off to a printing company you should ask them for details.

[Ofnuts]

(02-09-2023, 08:40 PM)Wallahoopi Wrote: Have a printer requesting 8.5"x11", 300 dpi, 1/8" bleed.

Have a GIMP doc at 2625x3375 and 300 ppi. Printer says it's coming up as wrong size and 72 dpi. 

Am I missing something or are ppi and dpi not comparable?

72DPI/PPI is the default value, so the actual definition is probably missing from the file. IIRC in some past 2.10 releases there was a bug that lost the image definition on export. What version are you running exactly?