DPI to pixels

Last updated: October 19, 2026

DPI alone does not convert to pixels

“300 DPI to pixels” has no single answer, because DPI is a density: pixels per inch of paper. It turns into a pixel count only once you know how large the print is. The relation is one line:

• pixels = inches × DPI
• pixels = millimetres ÷ 25.4 × DPI (25.4 mm to the inch)
• inches = pixels ÷ DPI, for the other direction

So one inch at 300 DPI is 300 pixels, a 4 × 6 inch print is 1200 × 1800, and A4 is 2480 × 3508. The results are rounded to the nearest whole pixel, which is how print shops and the usual reference tables count.

Photo sizes in pixels

Paper and poster sizes in pixels

Posters from A2 or 18 × 24 inches up are usually seen from a metre or more away, and print shops often accept 150 DPI for them. The 300 DPI column is what a photo book or a flyer held in the hand needs.

How many MB is a 300 DPI image?

DPI does not set the file size; the pixel count and the compression do. What the pixels cost before compression is easy to work out: width × height × 3 bytes for an ordinary colour image. A4 at 300 DPI is 2480 × 3508 pixels, so about 25 MB uncompressed; a 4 × 6 inch photo at 300 DPI is about 6 MB. Saved as a JPEG, the same image is usually a small fraction of that — how small depends on the picture and the quality setting.

So “300 DPI in KB” has no fixed answer either. When a form asks for “300 DPI and under 100 KB”, those are two separate conditions; resize the image to a KB limit handles both at once. The calculator above shows the megapixels and the uncompressed size next to every pixel answer.

The other direction: how large will my pixels print?

Divide the pixels by the DPI to get inches, then multiply by 2.54 for centimetres. These are the long sides of files people commonly have:

That is why a screenshot rarely makes a sharp A4 print, while an ordinary phone photo covers A4 at 300 DPI with room to spare.

“72 DPI to 300 DPI” does not add pixels

Changing the DPI number in a file does not change its pixels. A 1920-pixel image tagged 72 DPI and the same image tagged 300 DPI are identical; the tag only changes the size the file claims to print at. If the pixels in the charts above are not there, the fix is a larger original, not a different number. When the pixels are enough and only the tag is wrong, the DPI converter rewrites it without re-encoding the image.

To see what a file declares now, check the DPI of an image; for the images inside a PDF, use the PDF DPI checker.

How to convert DPI to pixels

The calculator above is already on “How many pixels?”, with A4 at 300 DPI.

1. 1

   Step 1: Enter the print size

   Pick a paper or photo size, or type your own width and height in mm, cm or inches.

2. 2

   Step 2: Choose the DPI

   300 for photographs and anything held in the hand; 150 for posters seen from a distance; 600 for line art and scans of text.

3. 3

   Step 3: Read the pixels

   The answer updates as you type, with the megapixels and the uncompressed size alongside. For the other direction, switch to “How large will it print?” and enter the pixels.

Frequently Asked Questions

Related Tools

• Convert an Image to 300 DPIRe-tag a JPG or PNG as 300 DPI without touching a single pixel — and see, before you send it, whether the file really covers the paper.
• Check the DPI of an ImageFind out what your file really declares — including the case where a JPEG declares two different values at once.
• DPI Calculator: Pixels, Print Size and DPIWork out how many pixels a print needs, how large a photo prints, or the DPI you actually get.