Question 1

Which AI model should you use for document translation?

Accepted Answer

The model that wins on single sentences is not automatically the model that wins on a 200-page document. For documents, the deciding factor is whether the model stays consistent with itself from start to finish.

What matters in a model for document translation

- Long-context retention: whether page 180 is still translated the way page 3 was
- Terminology control: whether a defined term survives unchanged, especially when a glossary is supplied
- Structural awareness: whether tables, lists, and headings are treated as structure rather than as prose
- Handling of things that should not be translated at all — code, formulas, part numbers, units
- Behaviour on the language pair you actually use, which can differ sharply from its average performance

Common mistakes when choosing

- Judging by parameter count or benchmark score instead of output on your document type
- Testing with one paragraph, which is exactly the case where all serious models look similar
- Ignoring consistency and grading only fluency — a fluent translation that renames a term every ten pages is worse than a plain one that does not
- Assuming the newest model is best for your language pair without checking

How to test a model on your own document

- Run the same real file through more than one model rather than a sample paragraph
- Search the output for a key term and check every occurrence matches
- Check tables and numbers before checking prose quality
- Repeat with a glossary attached to see how well the model honours it

Where to compare

Belin Doc lets you pick the model per job — see the available models for what each one is suited to, and premium translation for the highest-fidelity pipeline.

Choose on whole-document consistency, not sentence-level polish. Test on your own file, with your own terminology, in your own language pair.

Question 2

How to extract text from a PDF and translate it

Accepted Answer

Try to select a sentence with your cursor. If it highlights, the PDF has a real text layer and can be parsed directly. If nothing selects, it is a scan and needs OCR first.

How to tell which kind of PDF you have

- Text-based: text selects and copies, search finds words, the file is usually small for its page count
- Scanned: nothing selects, search finds nothing, the file is large because every page is an image
- Mixed: common in real documents — a digital report with scanned appendices or signed pages
- Deceptive case: a scan that already carries an invisible OCR layer will let you select text, but the selection lands in the wrong place

Extracting from a text-based PDF

- Parse the text layer directly, keeping reading order rather than page coordinates
- Handle tables and multi-column pages separately, or two columns get merged into one sentence
- Keep headers, footers, and footnotes out of the body text
- Convert to Word or Markdown first if you need to edit before translating

Extracting from a scanned PDF

- Run OCR to produce a text layer, then verify it before translating
- Flatten multi-layer scans with Flatten PDF so OCR does not run over existing hidden text
- Expect tables and formulas to need manual repair

Why extraction order matters for translation

Text pulled out in the wrong order gets translated in the wrong order, and no translation model can recover the intended meaning from scrambled input. Extraction quality caps translation quality — see why PDF translation breaks.

Identify the PDF type first. Everything downstream — extraction method, cost, and achievable quality — follows from that one answer.

Question 3

How to translate engineering drawings and technical PDFs safely

Accepted Answer

In a drawing, some text is language and some text is specification. Translating the second kind does not produce a bad translation — it produces a wrong part.

What must never be translated in a drawing

- Dimensions, tolerances, and units — a converted or reformatted number is a changed specification
- Standard designations and material codes (ISO, DIN, ANSI, GB references)
- Part numbers, drawing numbers, and revision marks
- Symbols for surface finish, welding, and geometric tolerancing
- Abbreviations that look like ordinary words but are defined terms in context

Why generic translation tools fail on drawings

- Drawings carry meaning through position: a note means something because of what it points at, and that link is lost when text is extracted
- Text is short and context-free, so a model has nothing to disambiguate from
- The language is bound to a technical standard, not to normal usage
- Vector line work and annotation layers are stored separately from the text
- A drawing exported as a scan has no text layer at all — see translating a scanned PDF

How to translate a drawing without changing it

- Freeze dimensions, units, symbols, and codes before translation begins
- Translate only explanatory text: notes, legends, title-block labels, revision descriptions
- Lock the terminology with a glossary so a term never varies between sheets
- Keep the source text visible alongside the translation so an engineer can verify rather than trust
- For drawing-specific handling, use the blueprint translator

Treat drawing translation as controlled technical work: decide what is frozen before you start, and have an engineer check the result against the original.

Question 4

What is Belin Doc, and what document formats does it translate?

Accepted Answer

Belin Doc is an AI document translator built around one requirement: the file you download should be usable straight away, with its layout, tables, and numbering intact — not a text dump you have to rebuild.

What formats it handles

- PDF, including scanned PDFs via OCR
- Word — note that Word files must be .docx; a legacy .doc needs to be saved as .docx first
- Excel and PowerPoint
- EPUB, TXT, and Markdown
- Images and photographed pages

What it does beyond translating the words

- Rebuilds the document structure rather than replacing text in place, so tables and multi-column pages survive
- Freezes Excel formulas so calculation logic is not translated — see preserving formulas
- Applies a glossary so terminology stays identical across a long file
- Offers side-by-side comparison of source and translation before you download

Related tools that come with it

- Split, merge, and compress PDFs
- Flatten scanned PDFs into a single layer
- Convert between PDF and Word, PDF and EPUB, and PDF and Markdown
- Video translation with subtitles and dubbing

Who it fits

- Anyone whose documents have structure worth keeping — specifications, manuals, financial models, papers
- Teams that need the same terminology across many files, via shared glossaries and organization accounts
- Organisations with data-residency requirements, via private deployment

The point of Belin Doc is what you get back: a document you can use, rather than a translation you have to reassemble.

Question 5

How to translate scanned PDF files and photos of documents

Accepted Answer

A scan is an image. There is no text in it to translate, so OCR must read the page first — which means recognition accuracy, not the translation model, sets the ceiling on quality.

How translating a scanned document works

- OCR converts the page image into machine-readable text
- The recognised text is checked, because every OCR error is about to be translated as if it were correct
- Translation runs on the text layer
- The layout is rebuilt so the translation sits where the original text was

What OCR gets wrong, and what it costs you

- Recognition errors are amplified, not caught: a misread word becomes a confidently mistranslated word
- Tables, formulas, and symbols are the first things lost — they often survive as plain text with the structure stripped
- Handwriting, stamps, and low-contrast scans drop out entirely
- Photographs taken at an angle or in uneven light lose whole lines
- If the scan already carries a hidden OCR layer, you can end up with two layers of text

How to get a better result from a scan

- Scan flat and straight at 300 DPI or higher, rather than photographing the page
- Flatten a multi-layer scan with Flatten PDF before submitting it
- Spot-check the numbers first — figures, dates, and part numbers are where OCR errors do the most damage
- Use the original digital file instead whenever one exists; it will beat any scan

How quota works for scanned pages

Scanned pages draw on the free OCR allowance in addition to your page quota, so a scanned file consumes more than a text file of the same length.

Related tools

- Free PDF translator
- How to translate a PDF

Translating a scan is really two jobs: reading it, then translating it. Improve the scan and the translation improves with it.

Question 6

AI document translation vs machine translation: what actually differs

Accepted Answer

The gain is not raw speed — classic machine translation was already fast. It is that an AI model can hold a whole document in view, so terminology and tone stay consistent from page 1 to page 300.

What AI document translation does that sentence-level translation cannot

- Keeps a term translated the same way throughout the file, instead of differently on each page
- Uses surrounding context to disambiguate — the same word in a contract and in a manual comes out differently
- Preserves the document's structure, so tables, headings, and lists survive the round trip
- Produces several target languages from one parse of the source

Where AI translation fits best

- Technical documentation, product manuals, and specifications, where consistency matters more than style
- Internal and reference material that needs to be readable, not publishable
- Multi-language releases where every version must ship at the same time
- Long documents where a human would lose consistency before reaching the end

Where it still needs checking

- Legally binding text, where a wrong word carries real consequences
- Marketing copy, which needs to be rewritten for a market rather than translated
- Figures, units, and part numbers — verify these rather than trusting them
- Anything where the source itself is ambiguous, since the model will pick one reading and commit to it

How the model choice changes the result

Different models handle long context and terminology differently, and the gap shows up on long documents rather than single sentences. See which AI model suits document translation and the available models.

AI document translation earns its place when a file is long, structured, and needs to stay internally consistent. For a single paragraph, the difference barely shows.

Document TranslationFAQ