Why Does My PDF Look Different on Another Device?

Fixed appearance is the entire promise of the format, so a PDF that renders differently on another machine is a genuine failure rather than a quirk. It is usually one of five things.

One: fonts were not embedded

By far the most common cause. The document names a font, the other machine does not have it, and something else is substituted — with different letter widths, so lines wrap differently and page breaks move. Check the Fonts tab in document properties; anything not marked embedded is a liability.

Two: the reader renders differently

Every reader has its own rendering engine. Anti-aliasing, hinting and transparency handling all vary, so text weight and shading can differ subtly between Acrobat, Preview, Chrome and a phone viewer. The layout is the same; the texture is not.

Three: colour handling

A document authored in CMYK for print, or one without an embedded colour profile, is interpreted by each device according to its own settings. Colours shift, sometimes considerably. Embedding a colour profile fixes it.

Four: transparency flattening

Drop shadows, soft masks and overlapping transparent objects are handled differently by different renderers. Older engines flatten them, sometimes producing visible seams or boxes where the effect was smooth.

Five: it is a scan

A scanned page is an image, and images are scaled by the display. On a low-resolution screen a 300 DPI scan is downsampled on the fly, which can look softer or sharper depending on the algorithm.

Making a document render consistently

1. 1Embed all fonts when exporting.
2. 2Embed a colour profile, or author in RGB for screen documents.
3. 3Flatten transparency yourself if the document uses heavy effects.
4. 4Convert to PDF/A, which enforces embedding and explicit colour.
5. 5Check it in at least two readers before sending.

When the difference matters

Font substitution changes pagination, and pagination matters in contracts, filings and anything with cross-references to page numbers. A document that is ten pages for you and eleven for the counterparty is a real problem, not a cosmetic one.