What Is the IMG369 Image DPI Changer?
This tool rewrites the DPI (dots per inch, sometimes called PPI) value stored inside a JPG or PNG file. DPI is a metadata field, not pixel data, so the image itself is completely unchanged; only the print-size hint that some software reads gets updated.
It's a metadata tool in the same family as IMG369's EXIF Remover and EXIF Viewer, editing what's recorded about an image rather than the image itself, but for a completely different reason: DPI has nothing to do with privacy, it's purely about how print and layout software interprets a file.
How It Works
A JPG stores its DPI inside a JFIF header block, and a PNG stores it inside a pHYs chunk. This tool reads your file's raw bytes, writes a fresh copy of the correct block with your chosen DPI value, and reassembles the file, entirely in your browser. The pixel data itself is never touched, copied byte-for-byte from the original.
Why Stock Photo Sites and Print Shops Ask for a Specific DPI
A common frustration: you upload a photo that's plenty large in pixels, say 3000x2000, to a stock photo site or a print shop's upload form, and it gets rejected or flagged for being "too low resolution," even though the pixel count looks completely fine. That's almost always a DPI metadata check, not a real quality problem. A camera or phone often saves photos at 72 DPI by default, a leftover convention from early screen displays, and some upload systems check that field specifically rather than calculating actual print resolution from pixel dimensions and target print size. The fix isn't to retake or enlarge the photo, the pixels are already there, it's to update the DPI field to what the platform expects, typically 300, which is exactly what this tool does without touching a single pixel.
Why DPI Matters for Print, Not Screens
A digital image is just a grid of pixels with no inherent physical size. DPI tells print and layout software how many of those pixels to pack into each inch of paper, which is why the same file can print small and sharp at 300 DPI or large and soft at 72 DPI. Web browsers and most apps ignore this metadata entirely and just show the image at its pixel dimensions, so don't expect any visual change on screen.
Common Uses
Meeting a print shop or stock photo site's stated DPI requirement, fixing a photo that opens too large or too small in a page layout program like InDesign or Word, or preparing a graphic that a client's printer expects at a specific resolution.
IMG369 vs. Other Ways to Change DPI
Photoshop can change DPI through its Image Size dialog, but you have to know to uncheck "Resample" first, otherwise it silently changes your pixel dimensions along with the DPI value, a common mistake for anyone not already familiar with that dialog. GIMP has a similar "Print Size" setting with the same resample trap. Free online DPI changers exist but need the file uploaded to their server. IMG369 changes only the DPI metadata, never the pixels, with no resample checkbox to get wrong, entirely in the browser.
| Method | Cost | File leaves your device | Risk of accidentally changing pixels |
|---|---|---|---|
| IMG369 | Free | No | None, DPI-only by design |
| Photoshop Image Size dialog | Paid subscription | No | Yes, if "Resample" isn't unchecked |
| GIMP Print Size dialog | Free | No | Yes, same resample trap |
| Typical online DPI changer | Free with limits | Yes, uploaded to a server | Varies |
Summary
IMG369's Image DPI Changer rewrites a JPG or PNG's print-resolution metadata to 72, 150, 300, or a custom value without touching a single pixel, entirely inside your browser with no upload and no signup. The sections above cover why a perfectly good photo can still get rejected for "low resolution" over a DPI metadata mismatch; the FAQ below covers format support and screen-display specifics.
Frequently Asked Questions
Does changing the DPI change how the image looks?
No. DPI is metadata, a note stored in the file about how many pixels should print per inch. It doesn't touch a single pixel, so the image looks and displays exactly the same. It only affects the physical size some print and design software will use.
Why does my image still look the same size on screen?
Web browsers display images by pixel dimensions, not DPI, so on-screen size never changes. DPI only matters to software that prints or lays out documents, like Word, InDesign, or a print shop's software.
What DPI should I use?
300 DPI is the standard for high-quality print (photos, flyers, business cards). 150 DPI is acceptable for less critical prints, and 72 DPI is the traditional default for screen-only images.
Does my image get uploaded anywhere?
No. The DPI metadata is rewritten directly in the file's own bytes entirely in your browser. Nothing is sent to a server.
Which file formats are supported?
JPG and PNG. Each format stores DPI in a different metadata block, and this tool writes the correct one for whichever you upload.