Bilingual books and facing-page layout
Two languages do not run to the same length. Translate a page and what comes back is longer or shorter than what you started with, and by how much depends on the language pair, the register and the translator. It is not a defect and you cannot edit it away.
That single fact decides the layout of every bilingual book, and almost nobody is warned about it before they have committed to a design.
Why facing pages drift
The picture in an author's head is a clean one: the original on the left-hand page, the translation on the right, the reader's eye moving across. It works perfectly for the first spread.
Then the translation runs long. By the third spread the right-hand page is half a page behind, by the tenth it is a page and a half behind, and the two sides are no longer talking about the same thing. The drift accumulates — every spread inherits the error from the one before it — so it does not correct itself anywhere in the book.
There are only two ways to force alignment back: pad the shorter side with white space, or squeeze the longer side with tighter setting, a smaller size or a narrower leading. Both are visible. Do it once and it reads as a design choice; do it on every spread for three hundred pages and the book looks unwell.
Option one: true facing pages
Source on the verso (the left-hand page), translation on the recto (the right). The rule that makes it survivable is that alignment is reset at a boundary, not maintained line by line. Each poem, each short piece, each numbered section starts fresh at the top of its own spread, and whatever white space is left at the foot of either page is simply left there.
This is why poetry is the natural case. A poem is a fixed block with a known length, it starts on a new page anyway, and a short page under it reads as normal typesetting rather than an accident. Scripture, aphorisms, letters, short parallel texts and language-learning readers all work the same way.
For continuous prose it works badly. A novel has no frequent boundaries to reset at, so the alignment either drifts or has to be manufactured on every spread. The chapter is usually the only reset point available, and a chapter is far too long an interval to hold two sides together.
Option two: sequential
The whole book in one language, then the whole book in the other. A half title or a section page divides them, the contents lists both, and the page numbers run straight through.
It is the easiest bilingual book to produce, it is the commonest shape for a bilingual novel, and it costs the reader almost nothing: a bilingual reader reads one version and dips into the other, and a monolingual reader ignores half the book. It also means each language is set the way it should be set, with no compromise made for the sake of the opposite page.
The obvious cost is page count. Two full versions is roughly twice the book, and page count sets the spine width and the printing cost.
Option three: interleaved by chapter
Chapter one in the first language, chapter one in the second, then chapter two, alternating through the book. Each chapter starts on its own page, so alignment never has to hold — the reset is built in.
It suits a reader who is working between the two languages, which is mostly language learners and parallel-text readers. It suits somebody reading straight through in one language much less, because they are turning past a chapter they are not reading every time.
In the Interior Formatter. It sets one text flow, so facing-page work means preparing the manuscript so the two sides land together — the tool will not shuffle them for you. Sequential and interleaved layouts are ordinary chapters, and it detects chapter starts even in a file with no styles. Start a book → · about the Interior Formatter
Getting the characters in intact
A bilingual book is full of accented letters, and accents are the quietest thing that can go wrong in a manuscript. A character that your screen shows correctly can vanish, or be silently set in a different face, in the printed file. All six body faces carry full Latin character sets, accents included, but check the export anyway — see Accents, symbols and characters that go missing.
Watch the punctuation too. Languages punctuate differently, and a translation typically arrives with its own conventions: guillemets for dialog, low-then-high quotation marks, spacing before a colon. Decide whether each language keeps its own rules or the book imposes one set, write the decision down, and apply it consistently.
Right to left is a different problem
Arabic, Hebrew, Persian and Urdu are not a harder version of this. They reverse the reading direction of the whole book: the spine is on the other side, the pages turn the other way, the cover is what a Latin-script reader would call the back, and the text itself needs proper bidirectional handling. That is specialist work in specialist software, not something to attempt in a general typesetting tool. Pairing a right-to-left language with a left-to-right one in one volume is harder again.
The book still declares one language
Metadata has one primary language field, and so does the EPUB. Pick the language a bookstore should file the book under — usually the one the buyer is searching in — and declare it. Individual passages in the other language can be marked as that language inside the file, which is what a screen reader uses to switch pronunciation, but the book as a whole gets one declaration.
The other side of that: an EPUB reflows, so facing pages cannot exist in one. A parallel layout has to become sequential or interleaved in the ebook, whatever the print edition does.
What most authors should do
Set poetry and short parallel pieces as true facing pages, reset at each piece. Set everything else sequentially. Reach for interleaving only when you know the reader is working between the two languages. The layout that looks most impressive in a sample spread is the one that is hardest to hold for three hundred pages.
Make yours
Everything here is built into the tools, and they are free to use: name your book, bring your manuscript or your artwork, and work as long as you like. You only pay when you want the files without the preview watermark.
Next: Setting poetry without wrecking it · More: Accents, symbols and characters that go missing · Translations and foreign rights, for a self-published author · EPUB and print PDF are two different books