The two formats set out to solve different problems in the first place.
In one line: PDF is a format for carrying paper around, EPUB is a format for reading comfortably on a screen. Neither is better; they have different jobs.
The gap shows up most clearly on a phone.
Open an A4-sized PDF on a phone and it stays A4. Fit it to the screen and the text is tiny; zoom in and you have to scroll sideways. That is not a flaw in PDF — it is exactly what "keep the layout fixed" means.
With reflowable EPUB, the text pours itself into the width of the screen. If a reader makes the type bigger, the book simply gets more pages, and it stays readable.
| EPUB (reflowable) | ||
|---|---|---|
| Changing text size | Readers set it freely | Zoom only |
| Reading on a phone | Comfortable | Depends how it was made |
| Layout fidelity | Varies by device | Always identical |
| Read-aloud | Easy to support | Depends how it was made |
| Printing | Not really suited | Its strong suit |
Whether the text size can change decides how many people can read the book at all. For a reader with weak eyesight, or an older reader, a book whose type cannot be enlarged is a book they cannot read.
If your work is mostly text and you are leaning towards PDF, this is worth holding in mind.
There is a difference in effort too.
Word, Illustrator and the like export it directly. If you have laid out a doujinshi carefully, or you want to hand out the same data you send to the printer, PDF is far less trouble.
For text-led work, EPUB gives readers a better experience. But the structure has to be built correctly, so a dedicated tool is really a prerequisite.
EPUB is also easier to fix later. Because the insides are HTML and CSS, correcting text or adjusting the design does not mean rebuilding the layout.
This may in fact be the single biggest factor in the decision.
So once you know where you are publishing, the format is half decided. If you are unsure, checking the requirements of the place you will publish is the shortcut.
Judging by the nature of the work, it comes out like this.
When the decision is close, the rule of thumb is simple.
"Will the reader read this on a screen, or print it?"
Screen means EPUB, paper means PDF. When it is read on a screen but the layout still has to hold — manga, for instance — fixed-layout EPUB answers both.
If you cannot decide, publishing both is an option.
In doujinshi distribution you often see a "PDF for printing" and an "EPUB for screens" bundled together. Readers pick whichever suits how they read, and you never have to commit to one.
It is more work, but if the original manuscript is the same, it is just two conversions. Depending on the work, that can be worth it.
Alongside image folders and text manuscripts, EPUB FACTORY can take each page of a PDF as an image and turn it into an EPUB. No account, no installation.
Try EPUB FACTORY