DPI converter
Free · Runs in your browser · Updated 17 October 2026
DPI converter
Settings
How to
Change the DPI of an image to 300.
- 1Choose your JPG or PNG images, or drop them on the box.
- 2Type the DPI you need, or tap 300 (print), 72 or 96 (screen), or another preset.
- 3Download each image; the list shows the print size at the new DPI.
What DPI is
DPI sets print size, not quality.
DPI (dots per inch, often meaning pixels per inch here) is a note in the file telling printers how many pixels to put in each inch. Changing it does not add or remove pixels, so the picture looks exactly the same on screen; only the printed size changes.
| DPI | Print size (inches) | Print size (cm) |
|---|---|---|
| 72 | 41.7 × 27.8 | 105.8 × 70.6 |
| 150 | 20 × 13.3 | 50.8 × 33.9 |
| 300 | 10 × 6.7 | 25.4 × 16.9 |
| 600 | 5 × 3.3 | 12.7 × 8.5 |
Print size = pixels ÷ DPI. When a form or print shop asks for “300 DPI”, they usually want the file marked 300 DPI and enough pixels for the print size: a 4 × 6 in print at 300 DPI needs 1200 × 1800 pixels.
Under the hood
Lossless, in both places the DPI is stored.
For JPG, the tool writes the DPI into the JFIF header (adding one if the file has none) and into the EXIF resolution tags if they exist, because Windows and some print software read one and some the other. For PNG it writes the pHYs chunk. The compressed picture data is not touched.
FAQ
Questions people ask first.
- How do I change the DPI of an image to 300?
- Open the JPG or PNG in the tool above, keep 300 in New DPI, and download it. The pixels stay the same; only the DPI setting changes.
- Does changing DPI change image quality?
- No. DPI is only a setting for printing. The same pixels print smaller at a higher DPI and larger at a lower one.
- How do I check the DPI of an image?
- On Windows: right-click → Properties → Details → Horizontal resolution. On a Mac: open it in Preview → Tools → Show Inspector.
- Why does my form ask for 300 DPI?
- So the picture prints sharply at the intended size. Set the DPI here, and make sure the picture has enough pixels for that size.
- Can I change the DPI of a WebP or HEIC?
- Not directly. Convert it to JPG or PNG first, then change the DPI here.
Related
More free tools.
- 4x6 photo size4 × 6 inches in pixels and centimetres, plus a tool that crops your photo to 4 × 6 or tiles smaller photos on it.
- Wallet size photo makerPut wallet-size (2.5 × 3.5 in) or passport photos on one 4 × 6 print, ready for any photo kiosk.
- Resize image to 20KBGet a photo or signature under 20KB for an application form, at the best quality that fits, with optional exact pixels.
- Remove EXIF dataStrip GPS location, camera and date from photos without re-compressing them.
From the team behind the tools
Need image handling inside your own app?
Daniotech builds web and mobile products, including upload flows that resize, convert and check images on the device before they reach your server.