Is your PDF A4
or US Letter?
A file can contain several paper sizes. Checking only the first page can miss the one that needs attention.
Check the whole file in three steps
- Open the checker and choose a PDF. The file is read locally. For a reproducible example, use “Try a sample” or download our four-page PDF.
- Review the size groups. Our sample has two A4 pages and two US Letter pages. Page 3 is rotated, but it is still A4 paper. By default, portrait and landscape pages share a size group.
- Choose the size you expect. Select the A4 group, then turn on “Show only pages of other sizes.” Pages 2 and 4 remain. Export the CSV if someone else needs the full page list.
A different size is not automatically an error. A booklet may intentionally contain a foldout. The sample has equally common sizes, so the tool asks you to choose a baseline instead of inventing a dominant size.
A4 and Letter, side by side
| Paper | Millimeters | Inches | Points (approx.) |
|---|---|---|---|
| A4 | 210 × 297 | 8.268 × 11.693 | 595.28 × 841.89 |
| US Letter | 215.9 × 279.4 | 8.5 × 11 | 612 × 792 |
A4 is 5.9 mm narrower and 17.6 mm taller than Letter. That difference can affect a layout fitted to the full sheet. These dimensions and the point conversion are documented in the PDF Association’s PDF/raster specification, Annex A.2.
Which unit should I use?
Millimeters are convenient for metric paper and print specifications. Inches make Letter and Legal easy to recognize. Points are useful when comparing PDF geometry with code. A standard point is 1/72 inch, so multiply points by 25.4/72 to obtain millimeters.
The PDF can also declare a page scale called UserUnit. PageCaliper applies that scale before reporting physical dimensions. Our boundary sample includes a page stored as 306 × 396 units with UserUnit 2: it measures a full 8.5 × 11 inches, not half a Letter sheet.
Why does a PDF look smaller than its paper size?
Paper geometry and visible geometry can differ. A MediaBox includes the full page extent, while a CropBox can hide its margins. A rotated page can also exchange the displayed width and height. Use the boundary selector to make sure you are comparing the same quantity in both tools.
For a concrete example with different boundaries, see our MediaBox, CropBox, and TrimBox guide. If you need to resize a document, edit the source layout or use a PDF editor; this checker leaves the original file unchanged.
What a dimension check cannot tell you
A correctly sized page may still contain low-resolution images or artwork that stops short of the bleed edge. A paper-name match is only a convenient label. Read the numerical dimensions and the printer’s specification before deciding what to change.
Ready to measure your document?
Open the PDF checker ↗