Change image resolution (DPI)
Change the dots per inch stored in an image and see how large it will print. Either rewrite the metadata only, or resample the picture to the paper size you need.
Drag your image here or click to choose it
Supports JPG and PNG (the DPI is stored inside the file itself)
72-96 DPI for screen, 150 DPI for home printing, 300 DPI for professional print.
What DPI is, and how it differs from resizing
DPI (dots per inch) does not change the image: it is a label stored inside the file telling the printer how large those pixels should be reproduced. A 3000 px wide photo measures 25.4 cm at 300 DPI and 50.8 cm at 150 DPI, with exactly the same pixels.
print size (inches) = pixels ÷ DPI
In metadata-only mode we rewrite the PNG pHYs chunk or the JPEG JFIF density, without re-compressing or rescaling anything: the file weighs the same and looks identical, but Photoshop, Word and the print dialog now read the new resolution.
print size (cm) = pixels ÷ DPI × 2.54
Resample mode does the opposite: you say what paper size you want and at how many DPI, and we compute and generate the pixels required. Here the image really does change, which is what makes this different from the resize tool, where you think in pixels instead of centimetres.
pixels needed = cm ÷ 2.54 × DPI
Worked example
Printing a photo at 10 × 15 cm with print-shop quality (300 DPI) needs 1181 × 1772 px. If your file already has them, just set the metadata to 300 DPI; if not, resample mode generates that image.
Frequently asked questions
- Does changing the DPI improve my photo?
- Not on its own. Without resampling the image holds exactly the same pixels; only the printed size changes. Real quality comes from the pixel count.
- Why am I asked for a 300 DPI image?
- That is the standard print-shop resolution. What actually matters is having enough pixels for the printed size: 300 DPI at 10 × 15 cm means 1181 × 1772 px.
- Does it work with WebP?
- The resolution metadata can only be written into JPG and PNG. With other formats use resample mode, which does generate the right pixels.
- How is this different from resizing an image?
- Resizing works in pixels ("I want 1200 px wide"). Changing the resolution works in physical size and DPI ("I want to print 10 cm at 300 DPI") and writes that resolution into the file.
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