There are four stages.
Of these, the first is what decides the result. With the preparation done, the conversion can be automated.
This is the most important part, and the part people most often miss.
Page order in an EPUB comes from the order of the file names. Name them wrong and the pages swap around.
Computers sort them as text, so without matching digit counts "10" lands before "2". Use a running number padded to the length your page count needs. Three digits past 100 pages, four digits past 1000.
001_cover.jpg — adding a description after the number is perfectly fine. As long as the name starts with a zero-padded number, the order stays stable.
These are the formats normally used in EPUB.
| Format | Suited to | Watch out for |
|---|---|---|
| JPEG | Photographs, colour illustrations | Compress too hard and it degrades |
| PNG | Line art, images with a lot of text | File size climbs quickly |
| WebP | When you need to keep the size down | Check reader app support |
For the body of a manga, JPEG is usually enough even for mostly-monochrome pages, though art with a lot of fine linework can look cleaner as PNG. PNG for the cover and JPEG for the body is a common split.
Bigger is not better. Too big and the file balloons and reading apps get sluggish.
Japanese manga reads right to left. Forget this setting and pages turn the wrong way.
In EPUB the setting lives in a file called content.opf .
| Value | Meaning | Books that use it |
|---|---|---|
rtl | Right to left | Japanese manga, vertical text |
ltr | Left to right | Horizontal text, Western-style books |
In a conversion tool it is usually presented as a "right-bound / left-bound" choice. Get it wrong and your readers start at the last page.
Manga often uses a spread — two pages as a single picture. There are two ways to handle one in EPUB.
Cut the spread down the middle and insert it as two images in order. The advantage is that every environment treats them reliably as pages. If the app supports landscape, they line up automatically.
Insert the wide image as a single page. The picture is not cut, but on a portrait screen it shows up small.
In practice, option 1 (splitting) is the safe one. How apps arrange spreads varies by implementation, and they do not always line up the way you intended. Consider option 2 only when cutting the artwork is unacceptable for the work itself.
Image-based EPUBs get large, unavoidably. A 200-page manga running to several tens of megabytes is nothing unusual.
A large file has knock-on effects.
The answer comes down to keeping the resolution to what is actually needed. Dropping in print-resolution data only inconveniences readers; on screen it looks all but identical.
When the conversion finishes, always check the display. The things to look at are fixed.
In particular, if you plan to publish on Kindle, checking in Amazon’s own preview tool is essential. Amazon converts the EPUB it takes in to its own format, so what you see in your own EPUB reader is not necessarily what readers get.
Pick a folder of numbered images and you get a fixed-layout EPUB with the binding direction and page size sorted out. No account, no installation.
Try EPUB FACTORY