How to Translate a PDF

Translating a PDF between English and Indonesian

A document in the wrong language is a locked door. A manual in English, a contract in Indonesian, a paper you need to understand today — machine translation is the fast way through, and a PDF is the hardest format to translate, because the text lives inside a layout that most translators cannot see. This tool translates the text of your PDF between English and Indonesian, in either direction, and gives you back a PDF you can read.

The translation is done by MarianMT OPUS-MT, an open-source translation model, running in your browser through Transformers.js. It translates sentence by sentence, so the meaning of each sentence is carried across on its own, rather than the whole page being guessed at once. One page of the original becomes one page of the translation, so the structure of the document survives — a three-page letter stays a three-page letter. If the translation is longer than the original, the extra text flows onto additional pages rather than being squeezed or cut. You can translate up to 20 files at once, 100 MB in total.

The honest limits matter more here than in most tools, because a bad translation looks confident. Only the text is translated — the layout is rebuilt, and tables, fonts, and images do not carry over. A table of numbers will come back as plain text, and a carefully designed page will come back plain. Quality also varies from sentence to sentence: everyday language translates well, but jargon, names, and legal text are weaker, and a single mistranslated word can change the meaning of a sentence. And the model downloads about 100 MB per direction the first time you use it — use Wi-Fi for that first run, and after that it is cached.

Use it for what it is good at: understanding a document, drafting a translation you will check, or reading a paper in the other language. Do not use it for a contract, a legal filing, or an official submission without a person checking every sentence. A machine translation is a draft, not a certified translation, and for anything that binds you, a human translator is the right tool. Keep the original alongside the translation so you can compare any sentence that looks wrong.

It also helps to know where translations go wrong, so you can spot the mistakes. Names of people and places are the first risk: a name can be translated as if it were an ordinary word, or left in the original language while the rest of the sentence moves on. Numbers are the second: a date, a price, or a measurement that comes out wrong is worse than a sentence you cannot understand, because it looks right. And a sentence that is long and complicated in the original will usually come out long and complicated in the translation — if a sentence confuses you in English, the Indonesian version will not make it clear. When a sentence matters, compare it with the original word by word, and if the two versions do not agree, trust the original and ask a person.

One more honest note: the translation is only as good as the text in the PDF. A PDF made from a clean document translates far better than a PDF made from a bad scan, because the text layer of a clean PDF is exact, while a scanned page has no text at all. If your PDF is a scan, OCR it first. And remember the direction: the tool translates between English and Indonesian only. A document in any other language cannot be translated here, and a document that mixes languages is unpredictable: the model treats all the text as the source language, so words in a third language may come out garbled.

Everything runs in your browser. Your document is never uploaded to a server, so a private letter or a business document stays on your device. There is no account, no daily limit, and no watermark. Open the tool, drop your PDF, pick a direction, and read the translation.

How to use this tool

1. 1Drop a PDF onto the Translate PDF page — up to 20 files, 100 MB in total.
2. 2Choose a direction: English to Indonesian, or Indonesian to English.
3. 3Press Translate PDF and wait while the model translates sentence by sentence.
4. 4Download the translated PDF and check it against the original.
5. 5For legal or official wording, have a person check the translation before you use it.