How to translate a PDF on your phone

To translate a PDF on your phone, open it in a document translation tool, choose the language you want, let it translate each page and save the result as a new file. On-device translation usually needs a one-time language download first, after which it works without sending your document anywhere. Scanned PDFs need OCR before they can be translated, because a scan is a picture with no text in it.

What happens when you translate a PDF?

The translation tool reads the text layer of each page, sends it through a translation model and writes the translated text back. A translation model is software trained on large amounts of text in pairs of languages, so it can turn sentences in one language into another.

There are two broad approaches:

Online translation sends the text to a server, which translates it and sends it back. It can be strong for many languages, but your document leaves your phone.
On-device translation downloads a language model to your phone, then translates locally. It is more private and works offline once the language is ready.

For anything personal, such as a tenancy contract, a medical letter or immigration papers, on-device translation is the more careful choice.

How to translate a PDF on your phone, step by step

Check the PDF has real text. Try selecting a word. If you cannot, it is a scan, and you need OCR first.
Open the file in a translation tool.
Choose the source language, or let the tool detect it.
Choose the target language.
If this is the first time you have used that language, wait for it to download.
Start the translation and let it work through the pages.
Save the translated copy under a new name and keep the original.
Skim the result, paying close attention to names, numbers and dates.

Translating scanned documents

Most official papers people need translated are scans or photos: letters, certificates, forms. For these, the order is:

Scan or photograph the pages clearly. See how to scan documents to PDF with your phone.
Run OCR to add a text layer. See how to make a scanned PDF searchable with OCR.
Translate the OCR'd file.

OCR mistakes carry into the translation, so a clean scan matters more than you might expect.

How accurate is machine translation?

Machine translation is good at getting the meaning of everyday text across. It is weaker in a few areas:

Legal and medical wording, where a precise term matters.
Names and addresses, which may be translated when they should not be.
Idioms and tone, which can come out literal or odd.
Tables and short labels, where there is little context.
Less common language pairs, which tend to be less polished.

Use machine translation to understand a document, reply to a letter or get the gist of a manual. For official use, such as court papers, visas or certified records, you usually need a human translation, often from a certified translator. Check what the receiving organization requires.

Will the layout stay the same?

Not exactly. Translated text is often longer or shorter than the original. Some languages run right to left, such as Arabic and Urdu, and some scripts need different fonts. A good tool tries to put the translation back in the same place on the page, but expect some text to be smaller, wrapped differently or tighter in its box. For long reports, a plain translated text version may be easier to read than a reshaped page.

Translating Word and text files

Translation is not just for PDFs. Many tools also handle Word documents and plain text files. If your source is a Word file, translating it directly can keep the formatting cleaner. If you only have a PDF and want to edit the translation afterwards, convert it first. See how to convert PDF to Word on Android.

Tips for better results

Translate a clean copy, without handwritten notes or stamps over the text.
Split very long files, so you can check each part as you go.
Keep the original alongside, and refer back to it for names and figures.
Check numbers by eye. Decimal points and date formats differ between countries.

Translating with PDF Burrow

PDF Burrow has a Translate tool that translates a PDF, Word or text file into another language, on the device and at no cost. The first time you use a language, the app downloads it once, and after that translation runs on your phone without uploading the document. For scans, run Make Searchable (OCR) first.

Frequently asked questions

Can I translate a PDF without internet?

Yes, with on-device translation, once the language has been downloaded. The first download needs a connection.

Is a machine translation accepted for official documents?

Often not. Many authorities ask for a certified human translation. Use machine translation to understand the document, then check what the receiving office requires.

Why did some words stay in the original language?

Names, brand terms and words the model does not recognize are often left as they are. OCR errors on scans can also stop words being recognized.

Can I translate just one page?

Usually. If your tool translates whole files, split out the page you need first, translate it, then keep it alongside the original.