A PDF is supposed to be the format where what you see is what you get — the "P" stands for portable. Yet a file that looks perfect on screen regularly prints with different fonts, dull colours, missing edges or unexplained grey rectangles. Each of those has a distinct cause. This page covers all of them and how to work out which one you have.
Diagnose it in thirty seconds
Open the PDF's document properties and look at the Fonts tab. If any font lacks "(Embedded Subset)" or "(Embedded)", that is your problem and everything else is secondary. If all fonts are embedded, the cause is colour, transparency or margins — covered below in that order of likelihood.
Missing fonts — the most common cause
A PDF handles fonts in one of two ways. It can embed the font data, carrying the actual glyph outlines inside the file, or it can reference the font by name and rely on the viewer to have it.
Referencing works fine on the machine that created the file, where the font is obviously installed. It fails everywhere else. The viewer or printer picks a substitute, and because different typefaces have different letter widths, the substitution does not merely change the appearance — it changes the layout. Line breaks move, text overflows its box, tables shift, and a carefully positioned page falls apart.
In Acrobat or most viewers: File → Properties → Fonts. Anything without "Embedded" beside it will be substituted on another machine.
⚠️ The 14 standard fonts are never embedded
The PDF specification defines fourteen base fonts — Helvetica, Times, Courier, Symbol and ZapfDingbats in their variants — that every viewer is required to provide. Files using them are smaller, and for decades this was considered good practice.
The catch is that "provide" does not mean "provide identically". One system substitutes Arial for Helvetica, another Nimbus Sans, another Liberation Sans. The metrics are close but not identical, so long documents drift and the last line of a paragraph can end up on the next page. For anything where layout matters, embed everything.
Why fonts sometimes cannot be embedded
Fonts are licensed software, and their licence includes an embedding permission flag with four possible values: installable, editable, print and preview only, or restricted — no embedding at all. When a font is flagged restricted, compliant software will refuse to embed it, and you will get a warning at export or silently get a substitution.
Commercial fonts from foundries sometimes carry restrictions. If a font refuses to embed, the practical options are to license it for embedding, or to switch to one that permits it — most open-source families such as those from Google Fonts allow embedding without restriction.
Fixing it
🚨 Converting text to outlines is not a general fix
Turning text into vector shapes guarantees it looks identical everywhere. It also makes the document unsearchable, uncopyable, and completely inaccessible to screen readers — and at small sizes outlined text often renders slightly heavier because it loses the font's hinting. Reserve it for logos and display type in artwork destined for a commercial press, never for body text in a document people will read.
Colour shifts
Screens and paper produce colour by opposite physical processes. A monitor emits light and adds wavelengths together — red plus green plus blue gives white. Ink absorbs light and subtracts wavelengths — cyan plus magenta plus yellow approaches black. These are not two ways of describing the same thing; they are different sets of achievable colours.
| Colour | On screen (RGB) | Printed (CMYK) |
|---|---|---|
| Vivid green | Brilliant | Noticeably muted |
| Bright orange | Glowing | Duller, slightly browner |
| Pure blue | Intense | Shifts towards purple |
| Neon and fluorescent | Fine | Impossible without a spot ink |
| Rich black | Absolute | Flat grey unless built as rich black |
Two specific problems account for most complaints.
Black that prints grey
Pure black in CMYK is 0/0/0/100 — black ink alone. On a large area that reads as dark grey rather than true black, because a single ink layer does not fully cover the paper. Designers use a rich black, adding other inks underneath: typically around 60/40/40/100.
The reverse is also a trap. Small text set in rich black requires four ink plates to align perfectly; any slight misregistration produces coloured fringes around every letter. Body text should always be 100% K alone. Rich black is for large solid areas only.
Overprint
Overprint tells the press to print one colour on top of another instead of knocking out the area beneath. It is deliberate for thin black elements, where it prevents registration gaps. It is a disaster when applied by accident to white objects — an overprinting white object is invisible in print while showing perfectly on screen.
Acrobat has an Overprint Preview mode (View → Show/Hide → Print Production) which renders the page as it will actually print. Anything that vanishes when you enable it is set to overprint. This is worth checking on any file going to a commercial press.
Transparency flattening
Drop shadows, soft glows, blend modes and partial opacity are all transparency effects. PostScript — the language most professional printers still speak — has no concept of transparency at all. So before printing, the PDF must be converted into opaque shapes that look like the transparent result. That process is flattening.
Flattening works by dividing overlapping regions into separate atomic shapes and calculating the resulting colour for each. Where it goes wrong you see:
- Visible rectangles — a faintly different background around a drop shadow or transparent image.
- Hairline seams — thin white lines crossing gradients, where adjacent flattened shapes fail to meet exactly.
- Text turned into images — text overlapping a transparent object gets rasterised, so it prints softer than the surrounding text and is no longer selectable.
- Colour shifts in the overlap only — a patch where the flattener chose a slightly different value.
✅ Export as PDF/X-4
PDF/X-1a requires everything to be flattened at export, which is where these artefacts originate. PDF/X-4 supports live transparency and defers flattening to the printer's own RIP, which is far better at it than an export dialogue. Unless your printer has specifically asked for X-1a, X-4 is the better choice and eliminates most flattening problems outright.
To find transparency in an existing file, Acrobat's Print Production panel has a Flattener Preview that highlights every affected object. If nothing lights up, transparency is not your problem.
Margins and scaling
The non-printable area
Every desktop printer has an edge it physically cannot reach, because the rollers grip the paper there. It is typically 3–5 mm on each side, and larger at the trailing edge on many inkjets.
A design that runs colour to the edge of the page therefore cannot print correctly on a desktop printer under any settings. There are exactly two options: leave a margin of at least 5 mm, or print on larger paper and trim it down — which is precisely what commercial printers do, and why bleed exists.
"Fit to page" quietly rescales everything
Most print dialogues default to a scaling option — "Fit", "Shrink oversized pages", or similar. This reduces the page by a few percent so that content clears the non-printable margin. It solves the cropping problem and creates a subtler one: everything is now 96% of its intended size.
For a report that does not matter. For anything where measurement matters — a technical drawing, a cutting template, a form designed to align with pre-printed stationery — it silently invalidates the output. Set scaling to Actual size or 100%, and if content then falls outside the printable area, fix the design rather than the print settings.
| Print setting | What it does | Use when |
|---|---|---|
| Actual size / 100% | No scaling | Almost always. Essential for anything measured |
| Fit to printable area | Shrinks by a few percent | Reading copies where exact size is irrelevant |
| Shrink oversized pages | Scales only pages that are too large | Mixed-size documents |
| Custom scale | Whatever you specify | Deliberate enlargement or reduction |
Image resolution
A PDF stores images at whatever resolution they were placed. A screenshot at 96 DPI dropped into a document and enlarged looks acceptable on screen — where the display is also around 96 DPI — and visibly soft in print, where the output device resolves four to six times finer.
Acrobat's Preflight can report the effective resolution of every placed image. As a rule of thumb, anything under 150 DPI at final printed size will look soft, and under 100 DPI will look obviously poor. Note that "effective" resolution accounts for scaling: a 300 DPI image enlarged to 200% is effectively 150 DPI.
PDF version and printer capability
PDF has gone through many revisions, and older hardware RIPs support older subsets. A file using features introduced after a printer's firmware was written may print incorrectly, or fail silently — a page emerges with an element simply missing.
Office printers are the usual place this appears, because they are replaced rarely. If a specific element consistently fails to print on one device and works on another, saving as an earlier PDF version is a reasonable test:
Print as Image — the reliable fallback
When you need the page to come out and diagnosis has run out of road, Print as Image rasterises each page into a single bitmap and sends that. It bypasses fonts, transparency, overprint and PostScript compatibility in one step, because none of those exist any more by the time the printer sees it.
The trade-offs are real: printing is slower, files sent to the printer are much larger, text is no longer selectable in the output, and fine detail softens slightly. Increase the resolution setting to 600 DPI if the option is offered.
In Acrobat it is under Print → Advanced → Print as Image. Treat a page that only prints correctly this way as a diagnosis rather than a solution — it tells you the problem is in the page description, which narrows things considerably.
A pre-print checklist
- Check fonts are embedded. Properties → Fonts. This is the first thing to rule out.
- Turn on Overprint Preview. Anything that disappears is set to overprint.
- Run Flattener Preview if the design uses shadows, glows or opacity.
- Set body text to 100% K, not rich black or a composite.
- Keep content 5 mm inside the trim, and add 3 mm bleed if it goes to the edge.
- Print at Actual size unless you deliberately want scaling.
- Verify image resolution is at least 150 DPI at final size.
- Export as PDF/X-4 for commercial printing unless told otherwise.
- Print one test page on the actual target device before committing to a run.
Need to rearrange pages before printing?
Rotate, split or merge PDF pages directly in your browser — the file never leaves your device, which matters for anything confidential.
Open the PDF Rotate Tool →Summary
- Unembedded fonts are the most common cause, and they change layout, not just appearance.
- The 14 standard fonts are substituted differently on every system. Embed everything.
- RGB colours that cannot exist in CMYK are remapped, always towards duller.
- Body text must be 100% K or registration will fringe it.
- Flattening artefacts come from PDF/X-1a. Use X-4 and let the RIP handle it.
- Every printer has an unprintable edge. Design 5 mm inside it.
- "Fit to page" silently rescales. Use Actual size for anything measured.
- Print as Image always works — treat it as a diagnosis, not a fix.
Frequently Asked Questions
Why do fonts look different when I print a PDF?
The font is not embedded in the file. A PDF can either carry the font data with it or merely reference it by name; if it only references, the printer or viewer substitutes the nearest available typeface. Since substituted fonts have different letter widths, text reflows and line breaks move — which is why a substituted document is not merely a different style but a different layout.
Why does my PDF print with a white border I did not design?
Every printer has a non-printable margin where the paper-feed mechanism grips the sheet, typically 3 to 5 mm on each edge. A design that runs to the edge of the page cannot be reproduced on a desktop printer at all. Commercial printing solves this by printing on oversized paper and trimming, which is what bleed is for.
Why do my colours look dull when printed?
Screens emit light and mix colours additively in RGB; paper reflects light and mixes subtractively in CMYK. The RGB gamut contains vivid colours — saturated greens, bright oranges, pure blues — that no combination of four inks can reproduce. Those colours are mapped to the nearest printable equivalent, which is inevitably duller.
What is transparency flattening and why does it cause grey boxes?
Older printers and PostScript devices cannot render transparency, so the PDF must be converted to opaque shapes before printing — that conversion is flattening. Where it goes wrong you get visible rectangles around transparent areas, hairline seams across gradients, or text that has been silently converted to an image. Exporting as PDF/X-4 avoids it because that standard supports live transparency.
What does Print as Image do?
It rasterises each page into a single large bitmap and sends that instead of the page's text and vector instructions. It bypasses font, transparency and PostScript problems entirely, so it is the reliable last resort — at the cost of losing selectable text, printing more slowly, and slightly softening fine detail.