Almost always a raster image whose effective resolution is too low for the size it is printed at, often because a small web image was scaled up. Upload the file and each image reports its measured effective DPI, so you can see exactly which one is soft rather than guessing.

Because a screen renders at roughly 96 DPI and upscales a low-resolution image smoothly, while a printer asks for far more detail than the image contains. A picture that looks acceptable at 100% on a monitor can be well under the threshold once it hits paper.

Upload it here and pick the profile that matches where the file is going. You get a score with itemised deductions plus checks across images, fonts, colour, page geometry, content, structure, security and accessibility — each finding located on the page it occurs on.

Usually oversized images stored at far higher resolution than they are displayed at, sometimes duplicated resources or unsubsetted fonts. The report shows each image with its pixel dimensions and its rendered size, which is normally enough to identify the culprit immediately.

The most common cause is a font that is not embedded, so the other machine substitutes a different one and the spacing shifts. Colour management and viewer differences account for most of the rest.

A PDF has no single DPI. Only the raster images inside it have a resolution, and what matters is the effective DPI — the image’s pixel dimensions divided by the size it is actually printed at. Around 300 DPI at final size is the usual target for print, with 600 for line art.

Upload the file: every embedded image is listed with its pixel dimensions, its rendered size in inches, and the effective DPI those two produce. That is a measurement rather than a stored value, which is why it can differ from the DPI the original image file claims.

Because effective DPI depends on how large the image is drawn. The same 800-pixel graphic is comfortably sharp in a thumbnail and badly soft across half a page. Resolution is a relationship between pixels and printed size, not a property of the file.

Usually because the graphic is not purely vector — it contains an embedded raster element, such as a placed photo or a rasterised effect. Vector artwork itself has no resolution; the raster inside it does, and that is what gets measured.

Which checks apply and how strictly. A file bound for a print shop is held to bleed, colour space and image resolution that would be irrelevant for an email attachment, and an editing profile cares about things a reader never sees. The same PDF can be fine for one destination and unusable for another.

It means no common blockers were detected for the profile you chose. Every deduction is itemised with the check it came from, its severity and how many times it occurred — so a score is a to-do list, not a verdict, and it is never a guarantee of acceptance.

The check could not be completed — an unreadable structure, content that could not be extracted, or an encrypted file. It is reported as its own outcome rather than being counted as a pass, because recording an untested check as passed is the most misleading thing a checker can do.

Yes, wherever the finding has a location. Selecting a check highlights the exact object that triggered it on the document preview — which is usually faster than reading a description and hunting for the image or text it refers to.

Run it against the professional print profile and read the blocking findings first: non-embedded fonts, low effective DPI, RGB content in a CMYK job, and missing bleed cause most rejections. Passing those does not guarantee acceptance, but failing any of them almost guarantees a rejection.

The recurring causes are fonts that are not embedded, RGB content where CMYK is required, images below the resolution minimum, and files that are not in the required PDF/X flavour. Check all four before re-uploading, since platforms usually report only the first failure they hit.

Bleed is artwork extended past the trim line — commonly 0.125 inches or 3 mm — so that when the guillotine cuts slightly off, no white edge appears. You need it whenever colour or imagery is meant to reach the edge of the finished page, and not otherwise.

The file has a structural problem — a damaged cross-reference table, a truncated save or a corrupt page — or it contains something the portal forbids, such as encryption or embedded JavaScript. Court and government filing systems reject on all of those.

RGB is how screens make colour and CMYK is how presses make it, and CMYK covers a smaller range. A vivid RGB image prints duller, and print workflows that require CMYK will reject a file containing RGB content — sometimes over a single image nobody remembered adding.

No, and no automated tool can. It runs the machine-testable checks and flags what fails, but reading order, alt-text quality and whether colour is the only cue all need a person. The dedicated accessibility checker explains that split in detail.

No. The report flags the issues that commonly break those workflows, which is a useful pre-check, but formal conformance is a certification question and should be confirmed with a validator built for it before anything is submitted as compliant.

Because they implement different rule sets at different strictness and make different judgement calls about ambiguity. A tool reporting fewer issues is not necessarily looking at a better document. Read the specific rule each one cites rather than trusting the totals.

No. It is read-only: your file is never modified and there is nothing to download. Each finding explains what to change and, where one exists, points at the tool that does that job. Fix at source where you still have the source, then re-check.

The PDF is sent over an encrypted connection, analysed read-only, and removed afterwards. It is not stored, shared, indexed or used to train models, and no account is required.