What Is a PDF Point (pt)? Convert Points to mm, Inches and Pixels
Open a PDF in almost any developer or design tool and sizes appear in "points". If you work in millimetres or inches, those numbers can look strange. Here is what a PDF point is and how to convert it.
Definition
One PDF point (pt) equals 1/72 of an inch. This is the default user-space unit defined by the PDF specification. Everything on a PDF page, from text size to object position, is placed in points measured from the page's origin.
Conversion formulas
- Points to inches: inches = pt ÷ 72
- Points to millimetres: mm = pt x 25.4 ÷ 72 (≈ pt x 0.3528)
- Points to centimetres: cm = pt x 2.54 ÷ 72 (≈ pt x 0.03528)
- Points to CSS pixels: px = pt x 96 ÷ 72 (= pt x 1.3333)
- Inches to points: pt = inches x 72
- Millimetres to points: pt = mm x 72 ÷ 25.4 (≈ mm x 2.8346)
Quick table
| Points | Inches | mm | CSS px |
|---|---|---|---|
| 1 | 0.0139 | 0.353 | 1.333 |
| 72 | 1 | 25.4 | 96 |
| 100 | 1.389 | 35.28 | 133.3 |
| 595.28 | 8.27 | 210 | 793.7 |
| 841.89 | 11.69 | 297 | 1122.5 |
Points vs pixels
A CSS pixel is 1/96 inch, so one point is 1.333 CSS pixels. A pixel in a raster image has no fixed physical size until you pick a resolution (DPI), which is a common source of confusion when converting between print and screen.
Switch units instantly
You don't need to do the math by hand. Open your file in PdfRuler and switch between pt, mm, cm, in and px; the rulers and status bar update right away. For standard page dimensions see PDF page sizes in mm, inches and points.
Frequently asked questions
How many mm is 1 PDF point?
1 PDF point is 0.3528 mm (25.4 ÷ 72).
How many points are in an inch?
There are exactly 72 PDF points in one inch.
Is a PDF point the same as a pixel?
No. A point is 1/72 inch; a CSS pixel is 1/96 inch, so 1 pt equals about 1.333 CSS pixels.
