How to Find the Page Size of a PDF (Acrobat, Preview, Browser, Online)
Before you print, upload or send a PDF, it helps to know its exact page size. Here are four ways to find it, from the fastest to the most involved.
1. Use an online PDF ruler (fastest)
Open PdfRuler, drop in your PDF and read the width and height from the status bar. Switch between mm, cm, inches, points and pixels with one click. Nothing is uploaded; the PDF stays in your browser.
2. Adobe Acrobat Reader
- Open the PDF.
- Go to File → Properties (or press Ctrl+D / Cmd+D).
- Check Page Size on the Description tab.
Acrobat shows the size of the current page only, so check each page if they differ.
3. Preview on Mac
- Open the PDF in Preview.
- Choose Tools → Show Inspector (Cmd+I).
- The General tab lists the page size.
4. Print dialog
Most PDF viewers show the paper size in the print dialog. This tells you what the viewer will print, which can differ from the PDF's real page size if scaling is applied.
Why the size might not match what you expect
- Mixed page sizes. A single PDF can contain pages of different sizes.
- Rotation. A landscape page may report width and height swapped.
- Page boxes. PDFs can define MediaBox, CropBox, TrimBox and BleedBox. The visible page size usually follows the CropBox or MediaBox.
- Rounding. A4 is exactly 210 x 297 mm but often stored as 595.28 x 841.89 pt, so tools may display slightly different rounded values.
Compare your result with standard paper sizes to see which one your PDF matches.
Frequently asked questions
How do I check the page size of a PDF for free?
Open it in a free online PDF ruler such as PdfRuler, or use File → Properties in Adobe Acrobat Reader or Tools → Show Inspector in Mac Preview.
Why does my PDF show a different size in different programs?
Programs may round values differently, apply page rotation, or read different page boxes such as MediaBox and CropBox.
