75 dpi a must?

I don't think it has to be exactly 75 dpi, just that they recommend it to be 75 dpi. My covers have varied quite a lot from book to book (not in the final product), but in the thumbnail. You can always upload a cover to see what it will look like. The thumbnail will show up in Amazon KDP after you upload the file so you can see for yourself how it will look before anything goes live.

It's a matter of memory size. A 300dpi image, rendered in jpg format measuring 240x480 occupies more memory space than a 75dpi image of the same size. Check the requirements for an avatar here on AW. It's a matter of memory. The file cannot be larger than #x# or larger than a specific #kb in size. It's the dpi (dots per inch which is a printer measurement and resolution) that sets the standard. 300dpi is considered the minimum "professional level" image standard for photographic images these days (the last I heard) which are intended to be printed. Note that most modern ink jet printers have resolutions of upwards of 1600dpi BTW because they're supposed to be capable of printing phot-quality images.

Always acquire the best quality image you can afford and then edit it down to the memory size required by the website or provider that's going to be holding the image. There are free programs that will do file size and image size conversions fairly routinely wthout (much) loss of resolution.

If it comes down to a question of resolution vs file size, stick with resolution. You want your cover images looking sharp and professional.

Sherrie, is it formatting you're wanting more information about or general tips? Smashwords has a Style Guide that is free and very helpful and Research Guy here on AW has a free book, as well.

Don't worry about dpi (dots per inch) unless you're planning on publishing in print format. What you do need to look at is ppi (pixels per inch), aka resolution. The higher the resolution, the clearer the image. Amazon is recommending your longest side to be 2500 ppi, just in case it should ever be printed. However, you don't have to do this since Amazon will re-size your image significantly down for its product page image. 1200x1600 is what a lot of designers are doing these days.

FOTSGreg said:

It's a matter of memory size. A 300dpi image, rendered in jpg format measuring 240x480 occupies more memory space than a 75dpi image of the same size.

Click to expand...

That's not accurate. A 240x480 image will be the exact same filesize regardless of whether the DPI is 75, 300, or a billion.

BrianJanuary said:

Don't worry about dpi (dots per inch) unless you're planning on publishing in print format. What you do need to look at is ppi (pixels per inch), aka resolution. The higher the resolution, the clearer the image. Amazon is recommending your longest side to be 2500 ppi, just in case it should ever be printed. However, you don't have to do this since Amazon will re-size your image significantly down for its product page image. 1200x1600 is what a lot of designers are doing these days.

Click to expand...

That's almost right, but you throw in "PPI" (pixels per inch) where you mean resolution (which is the fixed number of dots/pixels without any relation to a number of inches.) PPI and DPI are effectively the same thing until you get into the highest circles of nerdiness. Resolution is what matters for ebooks.

DPI/PPI is just for print. The raw resolution is what matters for an ebook and the DPI/PPI set will be ignored. 1200x1600 as Brian mentioned is a good baseline for ebook only and should meet all major retailers current requirements if I recall.

If you plan to do print then you'll likely want higher resolution than that, but that's a whole other discussion and does require consideration of DPI/PPI.

Also, I don't really understand the OPs comment about changing the DPI will change the Aspect Ratio. Just won't happen in any program I've ever seen so I wonder if something else is going on there...

http://www.andrewdaceyphotography.com/articles/dpi/

I just wanted to throw that article in here.

Arcadia Divine said:

http://www.andrewdaceyphotography.com/articles/dpi/

I just wanted to throw that article in here.

Click to expand...

That's a really helpful article. I've been using DPI and PPI like they're interchangeable all this time. Thank you!

Wow. Lots of confusion here. How about a simple set of guides:

DPI - Dots Per Inch - Print Resolution
PPI - Pixels Per Inch - Screen Resolution

PPI is fixed for monitors, usually 60 PPI or 72 PPI (PCs) or 96 PPI (Macs). Other devices may have fixed resolutions as well. PPI doesn't matter. Ever.

DPI matters for printed items only. The printed images looks "sharper" at a higher DPI. A newspaper on newsprint is about 150 DPI. Books will normally be 300 DPI. Photographs can be much higher.

What matters, in electronic publishing, is the image dimensions in pixels and, to a certain extent, the color depth. In print, a cover might be 6 inches wide by 9 inches high. It doesn't matter how many DPI are on that cover, the cover is still the same size.

Amazon, last I checked, suggests a cover of about 1500-2400 pixels long with a 1.6 ratio to the short side (The golden ratio, a good one to follow). That means if you choose 2000 pixels on the long side of your book, you divide that 2000 by 1.6 to get the short side, or 1250 pixels.

It really is that simple. Forget DPI. Forget PPI. For an eBook in a Kindle format, make the cover from 1500 to 2400 pixels high and divide that by 1.6 to find the width. Fit your cover in it. Done.

Your graphics program should be able to set the canvas size by pixels. You just need to stay within it.

Or hire it done.

Jeff