DPI is just a label that tells printers how big to print the pixels. Printers, journals and application portals often insist on "300 DPI", which this tool sets in the file header without touching the pixels. If you also need the right pixel count for a physical size, pick a print size and the image is resampled to match.
What is Change DPI?
This tool lets you change DPI of image files to 72, 96, 150, 200, 300 or 600 by rewriting the resolution value stored inside a JPG or PNG. It is the quick fix when a printer, journal, publisher or application portal insists that files must be 300 DPI and rejects what your camera or phone produced.
Optionally, it can also resize the image to a physical print size such as 4×6 inches, A4, US Letter or a 35×45 mm photo, so the pixel count actually matches the DPI you set. It handles batches too.
How to change DPI
- Drop JPG or PNG files.
- Choose the DPI (300 is the print standard).
- Optionally pick a print size, then download.
How Change DPI works
DPI (dots per inch), or more accurately PPI for digital files, is a single number saved in the file header. It tells software how many pixels to squeeze into each printed inch. It does not change the pixels themselves. A 3000-pixel-wide photo labelled 300 DPI prints 10 inches wide, while the same pixels labelled 72 DPI print almost 42 inches wide.
That is why print quality really depends on pixel count. For a sharp 300 DPI print, multiply the inches by 300: a 4×6 print needs 1200×1800 pixels and A4 needs 2480×3508. When you pick a print size here, the image is resampled to those exact pixels and centre-cropped to the paper's ratio, matching portrait or landscape to your photo.
For JPGs the tool writes the value into the JFIF header, and for PNGs into the pHYs chunk, both in your browser.
Key features of Change DPI
Free 300 DPI conversion
Set any of six DPI values on a batch of JPG and PNG files, with no watermark and no file count limit per batch. Process a whole folder and download everything as a ZIP.
Pixel count left alone
With No resize selected, the width and height stay exactly as they were and only the resolution value changes. PNGs are rewritten losslessly, and JPGs are re-saved once at 95% quality, which is visually identical.
Header edit in a blink
Changing a DPI value is a small header edit, so each file is ready almost instantly. Even with a print-size resize, a typical photo finishes in a second or two because nothing travels to a server or waits in a queue.
Desktop, tablet or phone
Runs in Chrome, Edge, Safari and Firefox on Windows, macOS, Linux, iOS and Android. Fix the DPI of a phone photo straight from your camera roll before uploading it to a print service.
Simple, accessible controls
Two labelled drop-down menus are all you need, and both work with Tab and the arrow keys. Progress is announced to screen readers, dark mode is available, and the layout holds up at high browser zoom.
Files processed privately
Manuscript figures, artwork and scanned documents are handled entirely in the browser tab and never leave your device. Check the network tab to confirm, and keep working offline once the page is open.
What makes EZ Compress's Change DPI different
Explains, then fixes
Many DPI converters imply that 300 DPI makes an image sharper. This tool is clear that DPI is a print label, and offers a real print-size resize when you need more pixels for the size you plan to print.
Seven print sizes built in
Pick 4×6 in, 5×7 in, A4, A5, US Letter, 35×45 mm or 2×2 in, and the tool calculates the pixel dimensions for your chosen DPI and crops to the right shape automatically.
Batch DPI changes
Set 300 DPI on fifty figures for a journal submission in one go, rather than opening and re-saving each file in an image editor. Every file in the batch gets the same setting.
Why use Change DPI?
Phones and many cameras save images at 72 or 96 DPI by default. That number does not hurt the picture, but upload checks for print-on-demand sites, thesis submissions, magazines and exam portals often read it and reject the file. Setting it to 300 DPI makes the file pass without changing how it looks.
Sometimes you need to change DPI of image files and hit a real print size at the same time. Choosing A4 or 5×7 here gives you the right pixel count and ratio in one step, so the print shop gets exactly what it expects and nothing is stretched or cropped unexpectedly at their end.
Who can use Change DPI?
Academic authors
Set figures and charts to 300 or 600 DPI before submitting to a journal or thesis portal that checks resolution on upload.
Print-on-demand sellers
Prepare artwork for mugs, posters and T-shirts at the 300 DPI value many print platforms require, with the pixel size to match.
Exam and government form applicants
Fix photos and signatures that a portal rejects for showing 72 DPI, without changing their pixel size or how they look on screen.
Self-publishing authors
Check and set the resolution of cover art and interior images to 300 DPI before uploading a book to a printing service.
Families printing photos
Resize phone photos to 4×6 or 5×7 at 300 DPI so a local print kiosk produces the expected size with no surprise cropping.
Settings explained
| Setting | What it does |
|---|---|
| DPI | Dots per inch written to the file header. 300 is the print standard. |
| Also resize to print size | Also resample the image so it prints at this physical size at the chosen DPI. |