No resampling · no upload

Change image DPI

Set a JPG or PNG to 300 DPI (or any value) for a printer, publisher or upload form. Only the resolution tag changes — the pixels, quality and file size stay exactly the same.

DPI, PPI and print size

A digital image has a fixed number of pixels. DPI (strictly, PPI — pixels per inch) is a number stored in the file that says how many of those pixels to place in each inch when printing:

print width (inches) = pixel width ÷ DPI
print width (cm) = pixel width ÷ DPI × 2.54

So a 2400 × 3000 pixel photo prints at 8 × 10 inches at 300 DPI, or 33 × 42 inches at 72 DPI — the same picture, just spread over a larger area. Changing the DPI value does not add or remove detail.

When you need to change the DPI value

• Print shops and photo labs that reject files labelled 72 DPI even when they have plenty of pixels.
• Book covers and interior images for publishers and print-on-demand services, which usually ask for 300 DPI.
• Application forms and ID photos that check for a specific DPI.
• Word, InDesign and PowerPoint, which use the DPI value to decide how large an image appears when you insert it.

If the print size at 300 DPI is smaller than you need, the image does not have enough pixels for that size. Upscaling adds pixels but not real detail; a higher-resolution original is the better fix.

What exactly is changed

For JPEG files the tool updates the JFIF header (adding one if it is missing) and the EXIF XResolution / YResolution tags if the photo has them, so Photoshop, Windows and macOS all report the new value. For PNG files it writes the pHYs chunk. Image data is not decoded or re-encoded.

Questions

Does it work for HEIC, WebP or TIFF?

Not yet — JPEG and PNG only. Convert other formats to JPEG or PNG first.

Are my images uploaded?

No. Files are read and rewritten inside this browser tab.

Windows still shows 96 DPI. Why?

Some apps cache file details. Close and reopen the folder or the file’s Properties window; the new value is stored in the file.