Change DPI
Set the resolution a print shop asks for — 300 dpi, 600 dpi or any value — right in your browser, without uploading the file.
Change the DPI of an image
DPI is not a property of the picture — it is a note attached to it. A file of 3000 × 2000 pixels holds exactly the same detail whether the note says 72 or 300; the number only tells a printer how large to lay those pixels out. At 300 dpi the same file prints 25 × 17 cm, at 72 dpi it prints 106 × 71 cm and looks coarse.
That is why "we need 300 dpi" usually means one of two things. Sometimes the file already has enough pixels and only the note is wrong — then changing the tag is all it takes, and the image itself stays byte-for-byte the picture it was. Sometimes the print really is too big for the pixels there are, and no tag will fix that.
This tool does the first job properly and shows you when you are in the second case. Drop a file in, pick a resolution, and it writes the value into the JFIF header, into the EXIF block if the file has one, and into the pHYs chunk for PNG — the places where design and layout programs actually look. The pixels are not re-encoded, so nothing is lost.
If you also need a specific print size, switch on the pixel option and enter the width in centimetres. The tool works out how many pixels that needs at your chosen resolution and resamples the image. It says plainly when the target is larger than the original: scaling up invents pixels and makes a picture softer, never sharper.
Privacy by design
All processing happens inside your browser. Your files never reach a server — there is nothing to store, transmit or share.
Learn more in our privacy policyFrequently asked questions
No. By default only the note in the file header is rewritten — the pixels stay exactly as they were.
Because DPI alone does not add detail. If a print at 300 dpi needs 3500 pixels and the file has 1200, the tag cannot make up the difference; you need a larger original.
300 dpi is the usual requirement for print, 150 for large formats seen from a distance, 72 or 96 for screens where the value is ignored anyway.
JPG and PNG. For JPG the JFIF header and any EXIF resolution are set, for PNG the pHYs chunk.
No. Everything happens in your browser; the file never reaches a server.
Yes — switch on the pixel option and enter the width in centimetres. The tool computes the pixels needed and resizes the image.