What is the appropriate file format for e-book covers on Kindle

alicat: You're AWESOME! I have scoured the Internet and never came up with this info (hopefully it is hard to find or I'm a terrible researcher!). Thank you so much! And your links are especially helpful! pharm: mobileread wiki is a trove I'm going to have to start going through. At first glance, though, it IS more detailed and will be extremely helpful. Thank you! As for your GIF suggestion. Perhaps I don't know how to properly work with GIF files (which I may not), but when I change my cover from JPG to GIF, the file size actually increases. I'm not sure how much it matters with my cover because it's a photo illustration. And although it's not very busy, it doesn't have a solid color background. But I'll try tweaking again in a GIF format. Thank you, again! You all have been great!!!

There's not really a standard size that works for all vendors—some care about minimum dimensions, others about maximum file size. For Amazon and Apple, our house standard is a 2400x3600 jpeg. Neither of them care about file size, but Amazon specifically wants a minimum of 1000px on the longer size, and advises that “https://kdp.amazon.com/help?topicId=A2J0TRG6OPX0VM.” B&N doesn't accept covers larger than 2MB, so we also generate a 1333x2000 jpeg and maybe jack up the compression a bit. Kobo wants covers to be smaller than 5MB, which is often the 3600, but not always. Note that at 1.5, this is the same aspect that 6"x9" trade paperbacks have, which can be convenient if you intend to also publish via CreateSpace. Kindles have a 1.6 aspect, though, so we're not filling the entire screen. The Kindle Fire HDX 8.9" has a screen resolution of 2560 x 1600, so if looking good on ALL Kindle devices is your goal, I'd assume that as a minimum size for feeding to KDP. I've never generated a Kindle book from a .doc—we feed ePubs into KDP for that—but your 17,000 word short story shouldn't be anything like 800K, once converted. The 75,000 word novel I published this morning is a 307K ePub, sans cover, and KindleGen just about doubles the size. If you're looking to shave bytes and your file is any bigger than 200K, you might want to see if Word is dumping buckets of unneeded styling in it (I'll bet it is).

The way you talk about dpi and resolution suggests that you're fiddling with values that you don't understand. Ignore the DPI - the Kindle is going to scale your cover to the size (subject to aspect ratio restrictions) regardless of the dpi. Do make sure you're saving the cover in a suitably compressed format - I have 2500x1600 images on my machine that are < 1Mb and are perfectly acceptable. JPEG at 85% quality (say) should be fine, or if it's a block colour image then a PNG (which is automatically compressed) might be better if Kindles will display them.

Thank you, everyone! I spent last night and today applying some of the suggestions and am in much better shape! bcwinters: Yes, I am working with the file as a JPG. I reduced the cover to 80% and that seems to be working well. I used the "Save for Web & Devices" feature. Thanks for the tip. mumkin: I adjusted the cover to 2560 x 1600 and that works great. Thank you for mentioning the unneeded styling that Word might be dumping into the file. I copy-and-pasted the text into a plain-text file and copy-and-pasted it back into Word, and that cleaned it up well, reducing the file from 450KB to 60KB! I have to go back and restyle the manuscript, but that's not a problem. pharm: I don't think Kindle will display PNGs (have to check into that for sure). I didn't think I had to worry about dpi and assumed I could set it to 72, but I came across numerous suggestions that advised against a dpi that low, saying you should have a dpi of around 300. All in all, I still can't get the whole file (story and cover) below 500KB before Amazon's conversion, which will put it somewhere around 1MB, but I'll keep working at it because that still seems large for a 17,000 short story. Thanks again!

If you want it any smaller, you're probably going to have to start using the command line tools to convert directly to a Kindle .mobi file directly from a suitable html file + metadata. Download http://www.amazon.com/gp/feature.html?docId=1000765211 from Amazon and have a play around.

Amazon says that KDP supports GIF, JPEG, PNG and BMP as image formats -https://kdp.amazon.com/help?topicId=A1B6GKJ79HC7AN - but the wording suggests that Kindles themselves will only display GIF or JPEG.

Pharm, thank you for checking on the image type. Amazon's wording is a little confusing. I've never used command line tools before, so thank you very much for the suggestion. I'm not sure how effective a novice like me will be, but I'll give it a try. Overall, reducing the file size of the image is driving me a bit nuts because I can't see how some of these books/short stories are as low as they are. I found one in the 170-range of kb for a 200-something page book with a nice cover. I asked a friend of mine who's a web designer, and he said the file sizes seem to be "impossibly low," but obviously it's being done, so there has to be a way. Thank you for your help! Any other suggestions, I'll take them. And if I find the solution, I'll post for anyone else down the road.

A cover with plain block colours, using the GIF format will be compressed to a very small file size - GIF compression works really well on areas that are all the same colour whilst preserving the sharp edges on text etc that jpeg tends to choke on. There's some useful information on generating Kindle mobi files on the mobileread wiki - it's quite a bit more detailed than Amazon's rather sparse documentation!

A few articles that may be helpful in reducing file size: http://bbebooksthailand.com/blog/ebook-file-size-minimize.html and http://www.creativindie.com/make-more-money-on-kindle-by-reducing-your-mobi-file-size/. One notable point is that the cover embedded in the ebook does not count toward the Kindle delivery charge. Also notable is that the physical file size of the MOBI eBook is not what Amazon will use to calculate the delivery fee.