Change Image DPI — Without Resampling
Set the print resolution recorded in a JPG — 300 DPI for print submissions, 600 for fine detail — without re-encoding the image. Only the metadata bytes change: the JFIF density fields and, when present, the EXIF resolution tags. Your pixels come out bit-for-bit identical, which is the whole point; nearly every other DPI tool quietly re-saves the JPEG and costs you a generation of quality to edit a number.
Drop JPG files here
JPEG only (this edits JPEG headers directly) · multiple allowed
How to change the DPI of an image
- Drop the JPGs in.
- Type the DPI you have been asked for — 300 is the standard print answer, 600 for line art and fine detail.
- Click Set DPI. Each result line shows the physical size the file will now print at, in both inches and centimetres, plus which metadata fields were updated.
The arithmetic, once
Print size = pixels ÷ DPI. Those three numbers are locked together, and changing the DPI tag changes only which of the other two you are describing:
- 1200×1800 px at 300 DPI → prints 4 × 6 in (10 × 15 cm).
- The same file tagged 72 DPI → prints 16.7 × 25 in, badly, at 72 dots per inch.
- A4 at 300 DPI needs about 2480×3508 px. Letter needs 2550×3300 px.
- Full-page magazine at 300 DPI is roughly 2550×3300 px — and if your source is a 1000 px web image, no tag will rescue it.
When a form rejects your "72 DPI" image
Check the pixel dimensions first. If they are large enough for the printed size the form wants, this tool is the entire fix — retag and resubmit. If they are not, you need a bigger capture or a bigger scan; upscaling invents detail that was never recorded, and reviewers can tell. The quality checker reports dimensions, megapixels, and the compression quality of any JPEG, which is usually enough to tell which situation you are in.
FAQ
Does changing the DPI improve my image?
No — and any tool that implies otherwise is misleading you. DPI is a note in the file's header saying "print me this big". Changing it from 72 to 300 does not add detail; it tells software to print the same pixels smaller and sharper. If a publisher says your image is "only 72 DPI", what they usually mean is that it does not have enough pixels for the size they need, and the fix is a bigger original, not a bigger number.
So when is this tool the right answer?
When the pixels are fine but the tag is wrong. Screenshots and camera exports are commonly tagged 72 DPI, and some submission systems reject them on the tag alone even though the pixel dimensions are ample. Word and InDesign also place images at their tagged size, so a 3000 px image tagged 72 DPI drops in absurdly large. Retagging fixes both, instantly and losslessly.
What does "lossless" mean here exactly?
The compressed image data is not decoded, re-encoded, or touched. Only the metadata bytes change: the JFIF APP0 density fields, and the EXIF XResolution/YResolution tags if the file has them. Pixel-for-pixel, the output is identical to the input — no generation loss, unlike every tool that re-saves the JPEG to change its DPI.
Why does it update two different places?
Because readers disagree about which one wins. JFIF density is the JPEG-native field; EXIF carries its own resolution tags, and Windows Explorer and Photoshop often prefer those. Updating only one is why "I changed the DPI but it still says 72" happens. Both are rewritten here, and the output line tells you which ones were found and updated.
I actually need the image resampled to 300 DPI at a specific size.
Then you want pixels changed, not tags: work out the pixel count you need (inches × DPI — a 4 × 6 print at 300 DPI is 1200×1800 px) and use Resize JPG to get there, then set the tag here.