Changing text in a PDF without changing its font

Why edited text so often changes font

A PDF does not say “this paragraph is in Georgia”. It says “draw glyph 41, then glyph 72, from this embedded font”. To keep files small, that embedded font is usually a subset: only the letters the document actually uses, renumbered in an order that only this file understands.

Many editors cannot read those private numbers, so they give up on the embedded font and type your new words in whatever looks similar on your computer — Times instead of Georgia, Arial instead of a brand font. The line then looks lighter or heavier, wider or narrower, and sits at a slightly different height. Worse, some editors show the original font while you type and switch only when they save.

How to keep the original font, weight and size

1. Edit the line, not a copy of it. In Edit PDF Text, click the line on the page and type. The new words are drawn with the document’s own embedded font, so the preview you see is the file you get.
2. Read the line’s style. The panel shows the font, weight and size the line already has. Leave “Original font” selected to keep them.
3. Watch for the warning. If you type a letter the PDF never contained, you are told before you save that it will come from a close match — and which letters.
4. Change the style on purpose. Size, bold, italic, underline, colour, alignment and a choice of open-licence fonts (Roboto, Open Sans, Lato, Montserrat, Playfair Display, Cairo, Amiri and more) are there when you want a different look.
5. Save and download. The rest of the page — pictures, lines, colours — is left exactly as it was.

When the original font cannot be kept

• New letters. A subset font only has the letters the document used. Typing “Zürich” into a document that never had a “Z” or a “ü” means those two letters come from a close match. Rewording to use letters already on the page often avoids it.
• Scans. A scanned page is a photograph: there is no text or font to edit until it has been read with OCR PDF. After OCR, edits are set in a matching standard font.
• Lines in several fonts. A line that mixes fonts (a bold word inside a sentence) is rewritten in its main font; you are warned before you type.
• Fonts the licence forbids. A few fonts are embedded “for viewing only”. They are still shown, but a close match is used for new words.

What to check before you send it

Open the downloaded file and zoom in on each changed line: the letters should match the line above and below in weight and width. Then compare the old and new versions with Compare PDFs, which highlights every word that changed — useful for catching a number you meant to keep. Search the new file for the old wording (Ctrl+F): it should not be found, because the old text is removed, not just covered.

If the document must not be changed again, Flatten PDF fixes the page as it is. For a signature, use Sign PDF after the text is final.