If you ordered the ebook directly from Amazon, then Amazon would automatically download the file size appropriate for your device. So they are providing a book optimized for several different platforms and devices. Some authors and publishers have problems optimizing their graphics and file sizes, but the Oreilly guys producing those ebooks are the best in the industry. (It's possible that O'Reilly has multimedia files which are causing the bloat, but i doubt it.) Amazon reduced the size and resolution of graphics to match the device. It looked perfect even at that smaller size. The Mobi file was 16mb, but after I uploaded it to the Kindle's Personal Document server, I think the Kindle e-ink device only needed to download a smaller 1.5 MB file size to the device. The epub file had high quality graphics and was 7.6 MB. I was testing an ebook before I published it on. Uploading it to first will let Amazon to send to device a file size appropriate for it. mobi file directly from the publisher, the preferred way to get it to your device is to upload it to Amazon's Personal Document Server which will feed it via wifi to your device.įor mobi files, I do NOT recommend trying to transfer it to your device via USB because it requires you to put a bloated file onto a device which may not be ready to process it. I don't know if it is a typo, but 60MB is a bit high for mobi files. I think 5.5 MB is a reasonable file size for an epub file.

The short answer is that with few exceptions you should NEVER need to scale down.

Calibre epub to mobi