Online Tool Store
Image DPI Changer
Update a PNG's DPI metadata for print workflows without touching a single pixel of the actual image. Runs entirely in your browser.
🔒 This tool runs entirely in your browser. Your files are never uploaded to a server.
How it works
- Choose a PNG image.
- Set your target DPI.
- Download the result — same pixels, updated DPI metadata.
The method
PNG stores resolution in an optional "pHYs" chunk as pixels per meter. This tool inserts (or replaces) that chunk right after the image header, leaving every pixel byte untouched:
pixels per meter = DPI × 39.3701
FAQ
Does this resize or resample my image?
No — not a single pixel is touched. Only the PNG's pHYs metadata chunk (which tells print software the intended physical size) is added or replaced.
Why would I want to change DPI without resampling?
Some print or publishing workflows check the DPI metadata to decide print size, even though the actual pixel dimensions stay the same — useful when you need software to treat an image as "300 DPI" without altering its resolution.
Does this work on JPEG files?
Not in this version — JPEG stores resolution in a different metadata structure (APP0/EXIF) than PNG's pHYs chunk. Only PNG is supported currently.
Is my image uploaded anywhere?
No — the PNG bytes are edited directly in your browser.
How we compare
| Feature | Online Tool Store | Resizing/resampling tools | Desktop image editors |
|---|---|---|---|
| Pixel data untouched | ✓ | ✗ | ✓ |
| No install | ✓ | ✓ | ✗ |
Resizing tools change your image's actual resolution. Image DPI Changer only edits the metadata a print workflow reads, leaving pixels exactly as they were.