Tiny Online Tools
The five boxes, seen rather than guessed
Every PDF page carries up to five boundary rectangles, and confusing them is how a job comes back from the printer trimmed wrong. PDF Page Box Editor draws all five over the rendered page, each in its own colour, so an off-centre TrimBox or a missing bleed is obvious rather than arithmetical.
What each box means
- MediaBox — the physical sheet. Everything else is clipped to it.
- CropBox — what a viewer displays. Defaults to the MediaBox.
- BleedBox — the area that reaches the press, including bleed.
- TrimBox — the finished page size after cutting. The box a printer actually needs.
- ArtBox — the extent of the meaningful content, as declared by the author.
MediaBox and CropBox are inherited through the page tree; the other three are not. The tool says, for every box, whether the page declares it, inherits it, or is falling back to a default — because "fixing" a box that was never there is a real way to break a file.
Editing
Work in points, millimetres or inches, on one page, a range like 1-3, 7, 9-, or the whole document.
- Offset from another box — grow or shrink edge by edge. This is how bleed is added: BleedBox = TrimBox + 3 mm, and one button does exactly that.
- Exact values, or a paper size (A3, A4, A5, Letter, Legal, Tabloid) centred on the reference box.
- Fit to visible content — render the page and take the bounding rectangle of everything that is not white. It is a measurement, not a reading of the content stream, and the tool says so.
- Remove — let the box fall back to its default.
Warnings that mean something
A box reaching past the MediaBox (viewers clip to it). A TrimBox not inside the BleedBox — reversed bleed, white slivers along the cut. Zero or negative area. A rectangle given from the wrong pair of corners, which plenty of software reads literally and turns into a negative size. And a missing TrimBox on a file headed for print.
Verified, not assumed
After writing, the produced bytes are parsed again from scratch and every box is read back and compared with what you asked for. The result table shows before, after and the check per page, with the edited document rendered beside it.
Privacy
The file is read and rewritten in your browser with pdf-lib and pdf.js. Nothing is uploaded, and your original file is never modified.