Translating PDF Files: Why Layouts Break and What to Do Instead

PDF is one of the most common file formats agencies receive from clients, and one of the worst starting points for a translation project. Knowing why, and what to do instead, saves money and avoids DTP problems that surface at the end of a project, when they cost the most to fix.

Why PDF is fragile

PDF was designed to look the same on every screen and every printer. That same design makes it hard to edit and translate.

A PDF does not store text as a flowing document. It stores lines and fragments of text at fixed positions on the page. An untagged PDF has no paragraphs or headings at all. A tagged PDF does mark headings and paragraphs, but only to describe the structure for assistive technology; the text still does not flow from one line or frame to the next as it does in Word or InDesign.

This is why editing a PDF directly is fragile, even in Adobe Acrobat, which does allow text editing. When a translated sentence is longer than the original, its text box grows or the text is squeezed, and neighbouring boxes do not move out of the way. Each box is independent, so nothing reflows.

The PDF-to-Word route: common but costly

The most widespread approach in translation agencies is converting the PDF to a Word document, sending it to a CAT tool for translation, then converting the translated Word back to a formatted file. This works up to a point.

The conversion from PDF to Word is imperfect by design. Conversion software has to guess at the document structure. It reads coordinates and tries to reconstruct a flowing document from a fixed layout. The result is often:

• Multi-column layouts that break apart or read in the wrong order
• Headings extracted as individual text fragments rather than coherent paragraphs
• Tables split into disconnected cells
• Line ends turned into paragraph breaks, which split sentences into separate segments in the CAT tool
• Paragraph order that does not match the visual reading order of the original

For a translator, this means a single sentence may appear as three separate segments, a heading appears twice, and translation memory suffers. The DTP work afterwards is far heavier than it would need to be.

When PDF-to-Word is acceptable

Not every project justifies a full InDesign workflow. For short, simple, text-heavy documents (a one-page letter, a simple form, a short press release), PDF to Word conversion is often the simplest route. It works when:

• The document has a simple, single-column layout with no complex tables or graphics
• The page count is low enough that manual cleanup is manageable
• The final delivery does not need to precisely match the original visual layout
• The client has no source files and cannot provide them

The right approach: work from source files

If the client has InDesign source files, use them. InDesign exports to IDML (InDesign Markup Language), which CAT tools such as Trados Studio and memoQ process directly. The translation happens inside the actual layout. Paragraph styles, fonts, spacing, and structure are preserved. Post-translation DTP is minimal.

Fixing the most common Trados error

When receiving IDML files for translation, a common error appears: Trados Studio refuses to open the file with the message:

The fix is simple and takes thirty seconds. There are two ways depending on whether you want to fix it for one project or for all future projects:

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When there are no source files: consider redesigning

If the document is short, up to fifteen or twenty pages, and the client cannot provide source files, it is often worth rebuilding it in InDesign from scratch instead of working from a converted PDF. This sounds counterintuitive but the maths work out.

A clean InDesign rebuild takes a few hours. The resulting IDML can be translated cleanly in a CAT tool. Post-translation DTP is minimal. Compare that with the hours spent cleaning up a broken PDF conversion, fixing missegmented CAT output and correcting the layout at the end, often in several languages.

Designing for translation from the start

The cleanest projects are those where the document was designed with translation in mind before anyone opened InDesign. A designer who understands multilingual DTP will:

• Use paragraph and character styles throughout instead of manual overrides
• Avoid forced line breaks (Shift+Enter) inside paragraphs; CAT tools split the segment there or show a tag mid-sentence
• Avoid typed hyphens for line breaks; they stay inside the word after translation and spoil translation memory matches
• Leave room in text frames: most European languages need about 30% more space than English
• Design in InDesign from the start and hand over the source files with the PDF

The last point carries the most weight in multi-language projects. A document going into thirty languages should be a clean, style-driven InDesign file. The IDML goes to translation, comes back, and the DTP work in each language is straightforward. A PDF converted, cleaned up, translated and reformatted thirty times repeats every problem thirty times.

A note on forced line breaks

Forced line breaks are one of the most common problems designers leave in translation files. A forced line break (Shift+Enter in InDesign) looks like a paragraph break on screen, but CAT tools treat it differently. Depending on the tool and its settings, the sentence is split into two segments at that point, or the break appears as a tag in the middle of the sentence. Either way, translation memory matches suffer, and the break ends up in the wrong place in the translated line.

The break is invisible unless hidden characters are shown, so it often goes unnoticed until the project is in translation.

Summary: how to choose your approach