Page sizes
A4, Letter, Legal, A3 and A5 in pixels
Exact pixel sizes of A4, Letter and three more pages at 72 to 600 dpi, how the numbers are worked out, and which setting to pick for screen, print and scans.
A page has a physical size in millimetres or inches. A pixel has no size at all until you say how many fit in an inch. That number is the resolution, in dots per inch (dpi). Every figure below is the page size in inches multiplied by the dpi, rounded to the nearest whole pixel.
The sizes
| Page | Millimetres | Inches |
|---|---|---|
| A5 | 148 x 210 | 5.83 x 8.27 |
| A4 | 210 x 297 | 8.27 x 11.69 |
| A3 | 297 x 420 | 11.69 x 16.54 |
| Letter | 215.9 x 279.4 | 8.5 x 11 |
| Legal | 215.9 x 355.6 | 8.5 x 14 |
Pixels at each resolution (width x height, portrait)
| Page | 72 dpi | 96 dpi | 150 dpi | 200 dpi | 300 dpi | 600 dpi |
|---|---|---|---|---|---|---|
| A5 | 420 x 595 | 559 x 794 | 874 x 1,240 | 1,165 x 1,654 | 1,748 x 2,480 | 3,496 x 4,961 |
| A4 | 595 x 842 | 794 x 1,123 | 1,240 x 1,754 | 1,654 x 2,339 | 2,480 x 3,508 | 4,961 x 7,016 |
| A3 | 842 x 1,191 | 1,123 x 1,587 | 1,754 x 2,480 | 2,339 x 3,307 | 3,508 x 4,961 | 7,016 x 9,921 |
| Letter | 612 x 792 | 816 x 1,056 | 1,275 x 1,650 | 1,700 x 2,200 | 2,550 x 3,300 | 5,100 x 6,600 |
| Legal | 612 x 1,008 | 816 x 1,344 | 1,275 x 2,100 | 1,700 x 2,800 | 2,550 x 4,200 | 5,100 x 8,400 |
Swap width and height for a page turned sideways.
Which resolution to use
- 72 dpi is the PDF's own unit. A PDF measures its pages in points, and a point is 1/72 of an inch, so an A4 page is 595.28 x 841.89 points inside the file. This is why a PDF page drawn "at 100 percent" is 595 x 842 pixels.
- 96 dpi is what Windows and web browsers treat as one CSS pixel per device pixel. An A4 page shown at 100 percent zoom on a normal monitor is 794 x 1,123 pixels.
- 150 dpi is enough for reading on screen and for casual printing. Text is crisp, and the file stays small.
- 200 dpi is the usual fax and archive standard, and the minimum most scanning guidelines ask for.
- 300 dpi is print quality. It is what a print shop expects, and what a scanner should be set to for documents you may need to print again. An A4 page at 300 dpi is 8.7 megapixels.
- 600 dpi is for line art, small type and archival scans. An A4 page at 600 dpi is 34.8 megapixels, and as an uncompressed image it takes 139 MB of memory. Only use it when you know why.
What this site's PDF to image tools produce
The PDF to JPG and PDF to PNG tools offer two settings. Screen draws pages at 1.5 times the PDF's own unit, which is 108 dpi, so an A4 page becomes 892 x 1,262 pixels. Print draws at 3 times, which is 216 dpi, so an A4 page becomes 1,785 x 2,525 pixels. That is above the 200 dpi archive standard and produces files about half the size of 300 dpi. If you need exactly 300 dpi, the resize tool will take the Print output to 2,480 x 3,508.
Working it out for any other size
Pixels = inches x dpi. For a size given in millimetres, divide by 25.4 first. A 100 x 150 mm photo at 300 dpi is (100 / 25.4) x 300 = 1,181 pixels wide and (150 / 25.4) x 300 = 1,772 pixels tall. Memory for the uncompressed image is width x height x 4 bytes, so that photo needs 8.4 MB while it is being drawn.