Change image DPI

How it works

DPI (dots per inch) is a number stored inside the image file. It tells printers and layout apps how large to print the pixels. This tool changes only that number. In a JPG it updates the resolution fields the file already has (JFIF, EXIF, Photoshop and XMP) and adds a JFIF field if there is none, or an EXIF field for JPGs saved with Adobe colour settings. In a PNG it writes the pHYs block. The picture data is copied byte for byte, so nothing is re-compressed, and the file size changes by under 100 bytes. Print size is pixels divided by DPI: a 1800 × 1200 px photo at 300 DPI prints at 6 × 4 in.

Questions

Are my images uploaded?

No. Everything runs in your browser, so your images stay on your phone or computer. Only the ZIP option downloads a small helper script the first time you use it.

Will a higher DPI make my photo sharper?

No. DPI only changes the print size; it does not add detail or sharpen the image. If the photo is too small at 300 DPI, you need a photo with more pixels — changing the number cannot create them.

What DPI should I use?

Follow what the form or print shop asks for. 300 DPI is the usual request for photo prints and documents; 72 or 96 is common for screens, where DPI is mostly ignored.

Which files work?

JPG and PNG. WebP, HEIC, GIF and TIFF are not supported, and damaged or cut-off files are left unchanged. Some apps ignore the DPI number or read only one of the fields, so they may still show their own default. Set the DPI as the last step: resizing or compressing in another app, for example with the compress image to exact KB tool, re-saves the image and may reset it.

Making a passport or visa photo?

Use the passport photo resizer to crop it to the right size first, then set the DPI here if the form asks for it.