PDF to image DPI: 72, 150 or 300, and what each is for

By the getPDF team · Published 11 October 2026

The short answer

DPI (dots per inch) decides how many pixels a PDF page becomes: page width in inches times DPI. Use 72 dpi for thumbnails and previews (an A4 page becomes 595 x 842 px), 150 dpi for screens, email and slides (1240 x 1754 px, the default), and 300 dpi for print or zooming (2480 x 3508 px). 600 dpi is for small crops such as a stamp or a detail, not whole pages.

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The Resolution row offers 72, 150, 300 and 600. The conversion runs on your device; nothing is uploaded.

DPI in plain words

A PDF page has a physical size, not a pixel size. A4 is 210 x 297 mm, which is 8.27 x 11.69 inches; US Letter is 8.5 x 11 inches. When the page becomes an image, each inch turns into as many pixels as the DPI says:

pixels = inches x DPI. A4 at 150 dpi: 8.27 x 150 = 1240 px wide.

So doubling the DPI doubles the width and the height, and makes 4 times as many pixels. That is why file size and time grow so fast as you go up.

Pixel sizes per DPI

Measured with PDF to JPG and PDF to PNG on 11 October 2026:

DPI	A4 page	US Letter page	Use it for
72	595 x 842 px	612 x 792 px	thumbnails, previews, chat
150	1240 x 1754 px	1275 x 1650 px	screens, email, slides (the default)
300	2480 x 3508 px	2550 x 3300 px	print, zooming into detail
600	3363 x 4756 px	3516 x 4550 px	small crops: stamps, signatures, details

The 600 row is capped. The converter draws at most 16 million pixels per page, because iPhones and iPads refuse to draw much larger pictures in a browser; a full A4 page at 600 dpi stops at 407 dpi, a US Letter page at 414 dpi. 300 dpi fits both. A crop does not hit the cap: a 42 mm square around a stamp, cut out with Crop PDF comes out at 992 x 992 px at 600 dpi, the full resolution. When a page hits the cap, the result says so and names the dpi it came out at, and each image records its real resolution, so a program that prints “at actual size” still prints it at A4.

What each DPI costs

1 A4 page at each DPI, JPG at quality 85 and PNG with a white background, measured on 11 October 2026:

DPI	Text page (44 lines of type), JPG / PNG	Report page (photo and text), JPG / PNG	Chart page, JPG / PNG
72	125 KB / 120 KB	91 KB / 188 KB	79 KB / 57 KB
150	403 KB / 430 KB	285 KB / 658 KB	237 KB / 208 KB
300	1.1 MB / 959 KB	788 KB / 1.9 MB	677 KB / 465 KB
600 (capped)	1.7 MB / 1.5 MB	1.3 MB / 3.1 MB	1.1 MB / 710 KB

Multiply by the page count for a whole file, then add a little for the zip. 20 text pages at 150 dpi as JPG came to a 753 KB zip; all 500 pages of our long text file at 72 dpi came to 5.1 MB and took 28 seconds on a mid-range 2024 laptop.

The same A4 page at 72, 150 and 300 dpi, drawn to scale by pixel count. Each step doubles the width and height and makes 4 times the pixels.

Which DPI for which job

72 dpi: thumbnails, previews, chat. Fine where the image is shown small. 10 pt text is about 10 px tall: readable at that size, blurry if anyone zooms in. A shop or library card is usually covered by 72 dpi; see a PDF cover thumbnail.
150 dpi: screens. The default, and the right answer for email, websites, documents read on a monitor and slides. A full HD screen is 1920 x 1080 px, so a 1240 x 1754 page already has more pixels than the screen can show at once.
300 dpi: print and zoom. For a page that will be printed at full size, or a detail people will zoom into. Print sizes and settings are in print a PDF right.
600 dpi: small crops. A stamp, a signature or a detail that will be enlarged. For whole pages it adds file size and time, not visible detail.

When unsure between 2 stops, take the higher one. You can always shrink an image; enlarging invents nothing.

Upscaling does not add detail

DPI only adds detail where the PDF has it. Text and drawings are vectors, so they gain real sharpness up to 300 dpi and beyond. A scan does not: its pixels were fixed by the scanner. Our test scan, a 148 x 105 mm page scanned at 200 dpi, holds 1165 x 826 px. Rendered at 600 dpi it becomes 3495 x 2478 px and 362 KB as JPG, against 31 KB at 150 dpi, with no letter any sharper.

For a scanned PDF, match the DPI to the scan (Inspect shows the stored picture’s pixel size; divide by the page width in inches), or take the scan out untouched with Extract images.

The honest part

DPI only means something relative to the size the image is shown or printed at. A 300 dpi image shrunk to a 200 px thumbnail wasted time and bandwidth; a 72 dpi image stretched over a slide looks soft however good the PDF was. Decide where the picture goes first, then pick the DPI.

This page is about turning a PDF into images. If you want to make a PDF’s own pictures lower resolution so the PDF gets smaller, that is compression, and reduce PDF DPI covers it. Everything else about getting pictures out of a PDF is in the pillar, PDF to images.

Questions

What DPI should I use to print an A4 page?

300 dpi. The page becomes 2480 x 3508 px, which prints at full A4 size without visible pixels. 150 dpi prints readable but soft text; below that, print looks rough.

What DPI does the tool use if I change nothing?

150 dpi, in both PDF to JPG and PDF to PNG. An A4 page then becomes 1240 x 1754 px, a good size for screens, email and slides.

Does a higher DPI make conversion slower?

Yes, roughly in step with the pixel count. On a mid-range 2024 laptop 1 A4 page took about 0.3 to 0.8 seconds at 150 dpi, 1 to 2.5 seconds at 300 dpi and 1.6 to 4.3 seconds at 600 dpi. 20 text pages at 150 dpi took 5 seconds.

Why is my 600 dpi image not 4961 pixels wide?

The converter draws at most 16 million pixels per page, so a full A4 page at 600 dpi comes out at 3363 x 4756 px, which is 407 dpi (a Letter page 414 dpi). The result says so, and the image records its real resolution. Small pages and crops (up to about A6) get the full 600.