Fonts and formatting

Why Words Run Together After Editing a PDF (and How to Fix It)

Updated 2026-09-17 · 2 min read

Three spacing faults show up again and again after a PDF edit: words joined together, a square box where a space should be, and gaps that are suddenly far too wide.

All three come from the same root cause — how spaces are encoded in a subset font.

PDFfont edits PDF text in the document's own embedded font — no white cover boxes.

Edit a PDF

The missing space

PDFs often do not store a space character at all. The gap between words is a positioning instruction, not a glyph. A naive editor writing a literal space produces text that runs together when the font has no space glyph.

The square box

A box (sometimes called tofu) appears when a space character is written using a code the subset font does not define. The reader has no glyph for that code and draws a placeholder instead.

The fix

Whitespace should never be drawn as a glyph in a subset font. PDFfont writes every space as numeric positioning inside the text-showing operator, which is exactly how the original document expresses its own spacing — so gaps match the surrounding text on the first edit and every edit after it.

Frequently asked

Why did only my first edit lose its space?

That was a bug pattern in tools that handle the first replacement differently from later ones. Whitespace here is positional in every case.

Can I fix a document that already has boxes?

Yes, re-edit the line and the whitespace is re-encoded correctly.

Do wide gaps mean the wrong font?

Often yes — a substituted font has different space widths.

Try it on your own document

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