PPI? Size in Pixels? What?

Your link didn't work for me. As you have been told, at least 300ppi. You really need to check with the printer for their exact requirements. That is the only way to avoid having someone mess with your image after you or other problems like being charged for extra prepress work. Most printers will want some bleed area so the image will need to be slightly larger than the printed size.

For best resolution, use 300 PPI. So a 10" x 8" picture would be 3000 x 2400 pixels. You can (according to their site) go down to 180 PPI, but I would use that only if the originals are small. Remember when resizing that enlarging a small picture will make it look blurry or pixelated.

You try to design an image in it's final size.

For example, if your cover's final size is to be six inches by nine inches, then your document size should be six by nine.

The resolution will depend on the publisher's need. Some will require a higher resolution than others. At the very MINIMUM, it will likely be at least 300 ppi. But some may require even higher resolutions, as high as 1200 ppi, or perhaps more.

Find out from mypublisher.com, what resolution is required.

Remember, you can always REDUCE the resolution of a finished graphic, but you cannot INCREASE the resolution. To be safe, design your cover in a higher resolution than you think may be required.

PPI means pixels per inch. Pixels are the same as dots in printing presses only it's the amount of the little lines of dots on computer screens. The common size is 72 ppi.

Usually high resolution images for books or magazines and covers go up to 6,000 dpi, or dots per inch, or over, but they have to be printed on special presses or off a computer printer that can print high resolutions. You can't print high resolutions off an ordinary printer. To get a proof, you need to take it to Kinkos or somewhere.

36 D