PDF Ruler Online: Free Ruler for Any PDF (mm, cm, inches)
A PDF ruler is a ruler you lay on a PDF page: real millimetres, centimetres or inches along the edges, so you can read how big anything on the page truly is. PdfRuler is a free PDF ruler online. It runs in your browser, so there is nothing to install and your file is never uploaded.
What does a PDF ruler do?
- Shows rulers in mm, cm, inches, points or pixels around the page.
- Reads the exact X/Y position of your cursor and the page width and height.
- Measures the distance between two points, or every box on the page automatically.
- Stays exact at any zoom, because it measures the PDF, not the screen.
How to use the PDF ruler online
- Open pdfruler.com/app and drop in your PDF (or press O).
- Pick a unit: mm, cm, in, pt or px.
- Hover for X/Y, click two points for a distance, drag from a ruler to pull a guide.
Why not just use a screen ruler?
A screen ruler measures pixels, and pixels change with zoom and display. An online PDF ruler works in PDF points (1/72 inch), so a page at 50% or 400% reports identical sizes. See PDF units explained.
Free and private
The PDF ruler is free, needs no account, and all work happens on your device. Good for contracts, drawings and print files you cannot upload. More: how to measure a PDF online and measuring without Acrobat.
Frequently asked questions
What is a PDF ruler?
A PDF ruler puts real-world rulers (mm, cm, inches, points) around a PDF page so you can read exact sizes and positions.
Is there a free PDF ruler online?
Yes. PdfRuler at pdfruler.com is a free online PDF ruler that runs in your browser with no account and no upload.
Does a PDF ruler work at any zoom?
Yes. PdfRuler measures in PDF points and converts to your unit, so every zoom level reports the same physical size.
