PDF Page Sizes in Points, mm and Pixels
Published by PDFToolz · Updated · Technical references listed below
A PDF measures pages in points. One point is 1/72 of an inch, so an A4 page is 595.28 by 841.89 points and a US Letter page is 612 by 792 points. Pixels only come in when a page is turned into an image, and then the count depends on the DPI you pick.
This guide lists the common page sizes in millimetres, inches, points and pixels at 72, 150 and 300 DPI, and shows the two formulas behind every number so you can work out any size yourself.
Page sizes table
Points are rounded to two decimals and pixels to the nearest whole pixel. Width comes first, for a portrait page. For landscape, swap the two numbers.
| Size | mm | Inches | Points | 72 DPI | 150 DPI | 300 DPI |
|---|---|---|---|---|---|---|
| A4 | 210 × 297 | 8.27 × 11.69 | 595.28 × 841.89 | 595 × 842 | 1240 × 1754 | 2480 × 3508 |
| Letter | 215.9 × 279.4 | 8.5 × 11 | 612 × 792 | 612 × 792 | 1275 × 1650 | 2550 × 3300 |
| Legal | 215.9 × 355.6 | 8.5 × 14 | 612 × 1008 | 612 × 1008 | 1275 × 2100 | 2550 × 4200 |
| A3 | 297 × 420 | 11.69 × 16.54 | 841.89 × 1190.55 | 842 × 1191 | 1754 × 2480 | 3508 × 4961 |
| A5 | 148 × 210 | 5.83 × 8.27 | 419.53 × 595.28 | 420 × 595 | 874 × 1240 | 1748 × 2480 |
How to convert mm to points and pixels
There are 25.4 mm in an inch and 72 points in an inch. Pixels per inch is the DPI you choose. That gives two formulas:
- Points = mm × 72 ÷ 25.4. For the 210 mm width of A4: 210 × 72 ÷ 25.4 = 595.28 points.
- Pixels = mm ÷ 25.4 × DPI. For the 297 mm height of A4 at 300 DPI: 297 ÷ 25.4 × 300 = 3507.87, which rounds to 3508 pixels.
- From inches it is simpler: points = inches × 72, and pixels = inches × DPI. Letter is 8.5 inches wide, so 8.5 × 72 = 612 points and 8.5 × 150 = 1275 pixels at 150 DPI.
- To go back, mm = points × 25.4 ÷ 72. A 500 by 700 point page is about 176.4 by 246.9 mm.
Why 72 DPI matches points one to one
At 72 DPI one pixel covers one point, so the pixel size equals the point size rounded to whole pixels. That is why an A4 page saved as an image at 72 DPI is 595 by 842 pixels. It is fine for a small preview but text looks blurry on most screens.
150 DPI is a good middle ground for reading on screen and sharing as an image. 300 DPI is the usual choice for print and for OCR, which reads text best when each letter has enough pixels.
Page size versus file size
Page size and file size are separate things. Changing A4 to Letter does not make a PDF smaller in MB, because the content stays the same. To make the file smaller, compress it. To change the page dimensions, resize the pages. To cut off white margins, crop them.
A PDF can also hold several page boxes. The MediaBox is the full sheet, and the CropBox is the part a viewer shows. When people talk about the page size, they almost always mean the visible CropBox.
Key takeaways
- ✓PDF pages are measured in points, and 1 point is 1/72 of an inch.
- ✓A4 is 595.28 × 841.89 points; US Letter is 612 × 792 points.
- ✓Points = mm × 72 ÷ 25.4, and pixels = mm ÷ 25.4 × DPI.
- ✓At 300 DPI an A4 page is 2480 × 3508 pixels.
- ✓Page size and file size are separate: resize changes dimensions, compression changes MB.
Tools for the job
Frequently asked questions
What is the size of an A4 page in points?
595.28 by 841.89 points, often rounded to 595 by 842. It comes from 210 by 297 mm multiplied by 72 and divided by 25.4.
How many pixels is an A4 page at 300 DPI?
2480 by 3508 pixels. At 150 DPI it is 1240 by 1754 pixels, and at 72 DPI it is 595 by 842 pixels.
What is the size of US Letter in points?
612 by 792 points, because Letter is 8.5 by 11 inches and each inch is 72 points.
How do I convert mm to points?
Multiply the millimetres by 72 and divide by 25.4. For example, 100 mm × 72 ÷ 25.4 = 283.46 points.
Does changing the page size make a PDF smaller?
No. Page size is the sheet's dimensions. File size depends on the content, so use compression to reduce MB.
Related terms
Browse every PDF term in the full PDF glossary, or head back to the PDFToolz toolkit.