Change image DPI
To change a photo to 300 DPI, drop the JPG or PNG here and pick 300. Only the DPI label changes, so the photo stays exactly as sharp.
Resolution
DPI is a label that tells printers and forms how large to print the image. The width and height in pixels stay the same, so the photo looks identical on screen. JPGs get the JFIF density and, if present, the EXIF resolution; PNGs get a pHYs chunk.
How did this tool do?
What DPI is, and why forms ask for 300
DPI (dots per inch) is a number stored in the file that tells a printer how many pixels to put in each inch of paper. It doesn't change the pixels at all. A 1200 × 1800 px photo at 300 DPI prints at 4 × 6 inches; at 150 DPI the same pixels print at 8 × 12 inches. On a screen, both look identical.
Exam portals, visa forms and print shops often check that the number says 300, and reject files that say 72 or 96, which is what many phones and editors write by default. This tool rewrites only that label. In a JPG it sets the JFIF density (adding a JFIF header if the file doesn't have one) and updates the EXIF resolution when there is one, because Windows and Photoshop read EXIF first. In a PNG it writes the pHYs chunk. The compressed image data is copied byte for byte, so the size in KB barely changes and nothing is re-saved.
If a form also wants a size in KB, compress first and set the DPI last. The print size shown under the button tells you how large the first image will print at the DPI you chose.
Where you'll meet it
Exam and job forms
Photos and signatures that must say 300 DPI.
Print shops
Files that should print at a known size.
Publishing
Images for documents and layouts that read DPI.
How to use it
- 01Pick a DPI: 300 is what most forms and printers ask for.
- 02Drop your JPG or PNG files.
- 03Tap Set DPI and download. The pixels are copied unchanged.
Image DPI, answered
Does changing DPI make my photo sharper?
No, and nothing can by changing DPI alone. DPI only says how many pixels go into each printed inch. A 1200 × 1800 px photo at 300 DPI prints at 4 × 6 inches; at 150 DPI it prints at 8 × 12 inches from the same pixels.
The form says 300 DPI and a size in KB. What do I do?
Compress to the KB limit first, then set 300 DPI here as the last step. Setting DPI only edits a label in the file, so it doesn't change the size in KB, while re-saving a photo in another app can reset the DPI.
Why does my phone photo say 72 DPI?
Many phones and editors write 72 by default because it means nothing for screens. It only matters when a form or a print shop reads it.
Are my images uploaded?
No. Everything happens in your browser, so your images never leave your device.