How to translate and read an EPUB
LangBox is an EPUB translator for reading: upload an ebook and each chapter shows the original beside the translation, with books under 10 MB translated in the background. Decide first whether you need to understand a book, read it in two languages, or download a new translated EPUB. LangBox does both: read each chapter in two languages, and once every chapter is translated, download a bilingual or translation-only EPUB.
Choose a format and prepare your reading
PDF keeps fixed pages and is useful when page layout matters. EPUB usually reflows its text when you enlarge the font, so it is often easier for long reading on a small screen. Image-only or fixed-layout ebooks may not reflow. OCR means turning a picture of text into selectable words; it does not translate. DRM means access protection that requires an authorised reader.
Start on a phone or tablet
Download the original sample first. Open an EPUB in an EPUB-compatible reading app using your device’s file/share menu; if the browser only downloads it, that is normal. Use the app’s font-size controls. In the LangBox web reader, sign in, select the translation language, then choose the EPUB from Files or Downloads. Use the chapter directory above the text on narrow screens and Translation mode to show only the translation. For PDF tables, a larger screen helps you compare columns. Desktop OCR commands are not phone instructions.
Return to a book
Wait until translations show as saved. Reopen the book from My ebooks. When browser storage is available, LangBox remembers the chapter and reading mode in this browser; it does not restore the exact line or sync this bookmark between devices. Clearing browser storage removes the bookmark, not server-saved translations. Public examples are demonstrations and start over on reload.
Before sharing a file
LangBox uploads and processes document content online. Do not upload confidential files or paste their text into an unapproved translator. Use a local reader/OCR tool or your organisation’s approved service instead. Local OCR and calibre repair do not themselves translate. A permitted, unprotected copy is needed; changing a filename does not remove DRM.
Understand token credits before uploading
The PDF and EPUB upload screens show your account token balance and the default model, with a refresh button. A balance is not a document quote. There is currently no reliable per-file price preview or hard spending cap. Tokens are pieces of text, not words or pages; input, output and additional model work affect usage.
Arithmetic example, not a file estimate: a request billed for 1,500 tokens consumes 1,500 credits at a 1× rate, or 5,625 at the current Gemini 3.8 Flash rate of 3.75×. Rounding is per request. These are account credits, not a currency price; a full book can involve many requests.
Unused reservations are returned. Requests recorded as failed release their reservations, but completed requests can remain charged even if the document later fails or is cancelled. Retries can consume more credits. Start with a permitted short excerpt or a small page range; do not assume cancellation refunds the whole job.
An EPUB below 10 MB automatically starts whole-book translation after upload. If you only want to test, make a separate short EPUB first. Original sample downloads and the examples on this page do not use model credits.
Choose the right method
Open the original and check its contents
Use an EPUB reader you already have. Open the table of contents, jump to the beginning, middle and end, and try selecting a paragraph. If the original itself is incomplete, translation will not restore the missing chapters.
Choose reading or file export
For a few passages, copy the selected text into a translator. For sustained reading, choose paragraph-by-paragraph bilingual display. If you need a translated EPUB for another device, confirm that EPUB export is explicitly supported before uploading or paying. LangBox exports a bilingual or translation-only EPUB once every chapter is translated.
Test one chapter with the original visible
Compare names, negation, dialogue and numbers. Switch between original and translated text to catch omissions. Book translations may choose different phrasing while preserving meaning; the prepared sample below demonstrates one possible rendering.
Check the whole book before relying on it
Visit chapters near the beginning, middle and end. Distinguish original paragraphs from completed translations and check that progress is finished. Keep the original EPUB as your reference. Saving a web page or printing it to PDF does not produce an EPUB.
Check your result
Download the sample and open it in an EPUB reader: there should be two entries in the contents, each with two English story paragraphs plus excerpt notes. On this page, switch excerpts and all three reading modes. In excerpt II, compare “more than nine feet” with its translation. This short sample does not verify a full novel, illustrations, DRM or complex formatting.
If something goes wrong
A chapter is missing
Compare the original reader’s contents with the imported list. If the original has the chapter, the ebook’s navigation or spine may be malformed. Re-export an unprotected copy from your ebook editor, then test it in a second reader.
Pages contain pictures, but no selectable words
This is an image-based ebook. Extract/OCR permitted pages using an appropriate local tool or obtain a text edition. A text-based EPUB translator cannot translate words it cannot extract.
The book is DRM-protected
Use a compatible authorised reader or request an unprotected edition from the publisher. Changing the extension from .azw or .pdf to .epub does not convert the book.
Only part of the book is translated
Check the job’s state and model-credit balance. In LangBox, files below 10 MB automatically queue whole-book translation; larger supported files use chapter translation. A visible chapter is not evidence that the whole book is finished.
One very long paragraph fails
A single segment above 20,000 characters cannot be translated by the current service. In an EPUB editor, split the text at meaningful paragraph boundaries, save a copy and check chapter order before importing again.
You need a translated file for a Kindle or another reader
When every chapter is translated, download a bilingual or translation-only EPUB from the translator at the top of this page or from the LangBox reader, then copy it to your device. The sample download on this page is the original English sample, not a translated book.
A local repair option
In calibre’s free Edit book tool, open a copy of the EPUB and run Tools → Check book. Review the reported errors, then use Tools → Table of Contents → Edit Table of Contents to inspect chapter links. Save the copy and test it in the reader again. Structural checks do not verify translation quality.
Official instructions · calibreRead an example first
Two short English excerpts from Alice’s Adventures in Wonderland (1865), with prepared translations. No account, upload or credits needed. This is an edited reading example, not a live translation or a benchmark of LangBox output.
English → Español
I · Down the Rabbit-Hole (Excerpt)
Original · English
Alice was beginning to get very tired of sitting by her sister on the bank, and of having nothing to do: once or twice she had peeped into the book her sister was reading, but it had no pictures or conversations in it, “and what is the use of a book,” thought Alice “without pictures or conversations?”
Translation
Alicia empezaba a cansarse mucho de estar sentada junto a su hermana en la orilla y de no tener nada que hacer. Una o dos veces había mirado el libro que leía su hermana, pero no tenía dibujos ni conversaciones. «¿Y de qué sirve un libro —pensó Alicia— sin dibujos ni conversaciones?»
Original · English
So she was considering in her own mind (as well as she could, for the hot day made her feel very sleepy and stupid), whether the pleasure of making a daisy-chain would be worth the trouble of getting up and picking the daisies, when suddenly a White Rabbit with pink eyes ran close by her.
Translation
Así que estaba pensando (tan bien como podía, porque el calor le daba mucho sueño y la atontaba) si el placer de hacer una guirnalda de margaritas compensaría la molestia de levantarse a recogerlas, cuando de pronto pasó corriendo muy cerca de ella un Conejo Blanco de ojos rosados.
II · The Pool of Tears (Excerpt)
Original · English
Just then her head struck against the roof of the hall: in fact she was now more than nine feet high, and she at once took up the little golden key and hurried off to the garden door.
Translation
Justo entonces, su cabeza chocó contra el techo de la sala: en realidad, ya medía más de nueve pies de altura. Enseguida recogió la llavecita de oro y se apresuró hacia la puerta del jardín.
Original · English
Poor Alice! It was as much as she could do, lying down on one side, to look through into the garden with one eye; but to get through was more hopeless than ever: she sat down and began to cry again.
Translation
¡Pobre Alicia! Tumbada de lado, apenas conseguía mirar al jardín con un solo ojo; pero atravesar la puerta era más imposible que nunca. Se sentó y empezó a llorar de nuevo.
Source and reuse details
Lewis Carroll · 1865. The original English text is public domain in the US. New sample formatting and translations are released under CC0. No modern published translation or illustrations are included. Public-domain status can differ by country.
Find the complete original book · Project Gutenberg #11CC0Source and reuse details (English)
Learning Spanish? Read a Spanish → English example
This newly authored, AI-assisted short story and prepared English rendering are released under CC0. They demonstrate reading in this direction; they are not live LangBox output.
La biblioteca
Lucía llegó a la biblioteca a las nueve. No buscaba un libro nuevo: quería devolver una novela y preguntar por el club de lectura.
Lucía arrived at the library at nine. She was not looking for a new book: she wanted to return a novel and ask about the reading club.
La bibliotecaria le explicó que el grupo se reunía el jueves, no el martes. Lucía anotó la fecha antes de salir.
The librarian explained that the group met on Thursday, not Tuesday. Lucía wrote down the date before leaving.
El camino
Al día siguiente, Lucía caminó doce kilómetros junto al río. Llevaba agua y un libro pequeño, pero no tenía prisa.
The next day, Lucía walked twelve kilometres beside the river. She carried water and a small book, but she was in no hurry.
Al llegar al puente, abrió el libro por el capítulo dos. Leyó durante quince minutos y dejó una nota para recordar dónde continuar.
When she reached the bridge, she opened the book at chapter two. She read for fifteen minutes and left a note to remember where to continue.
Check “el jueves, no el martes”: the meeting is on Thursday, not Tuesday. Keep the twelve-kilometre distance separate from the fifteen-minute reading time. In the EPUB reader, choose English before uploading the Spanish source.
Spanish source EPUB · two short chaptersSource and CC0 details