See and change the DPI stored in a JPG or PNG without touching the pixels, or resize it for an exact print size. Everything runs locally in your browser - your files are never uploaded to a server, no registration is required, and the tool is completely free.
How to Change Image DPI
Choose a JPG, PNG or WebP image. The page shows its pixel size and the DPI the file currently stores.
Pick 'Change DPI only' to relabel the file, or 'Resize for print' to set a physical width and height in mm, cm or inches.
Enter the DPI or tap 72, 96, 150, 300 or 600.
Save and download. The page reads the DPI back from the new file so you can confirm it.
Features
Lossless DPI change: For JPEG the JFIF header (and EXIF resolution, if present) is rewritten and the image data is copied byte for byte. For PNG the pHYs chunk is set. No pixel changes.
Resize for an exact print size: Enter a size such as 10 x 15 cm at 300 DPI and the image is resampled to the pixel count that needs, with the DPI stored.
Shows what the file claims now: Read the current DPI from the file's own header, and see how large it prints at that DPI.
Warns about enlarging: If a print size needs more pixels than the image has, you are told it will be enlarged and may look soft.
Frequently asked questions
Does changing DPI improve quality?
No. DPI is only a label that tells printers and word processors how big to make the image. Quality depends on the number of pixels, which 'Change DPI only' leaves exactly as they are.
A form asks for a 300 DPI photo. Which mode do I use?
If it only checks the DPI value, use 'Change DPI only'. If it also gives a physical size, use 'Resize for print' so the pixel count matches that size at 300 DPI.
Why can't I change the DPI of a WebP?
WebP has no DPI field that print software reads. 'Resize for print' saves such images as PNG with the DPI stored.
Why does my photo show no DPI?
Many files store none, or store only an aspect ratio. Most programs then assume 72 or 96 DPI.