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What you are actually looking for
Two numbers decide whether a file prints properly, and only one of them is the DPI:
- The pixel dimensions — how much real detail exists. This cannot be changed after the fact.
- The declared density — the number in the header saying how big those pixels want to be on paper. This is the DPI, and it is only a label.
Drop a file below and both are read out, together with the physical size the file will print at. Nothing is changed and nothing is uploaded; this is a read, not a conversion.
Why a JPEG can report two different DPI values
A JPEG can carry a density in two independent places: the JFIF header at the start of the file, and the EXIF resolution tags written by the camera or editor. Nothing forces them to agree, and after a few round trips through different software they frequently do not.
This is the situation behind the most frustrating kind of rejection — the file that gets refused twice for the same reason after you “already fixed it”. Your tool wrote JFIF; the prepress software read EXIF; both were telling the truth about different fields. The reader below reports every place a density was found and says explicitly when they disagree, which most DPI checkers do not.
Why a PNG often reports nothing at all
PNG stores density in an optional `pHYs` chunk. Plenty of PNGs — screenshots above all — simply do not have one, and a file with no `pHYs` is not declaring 72; it is declaring nothing, and each program that opens it falls back to its own assumption. That is a genuinely different state from “72 DPI”, so it is reported as its own answer rather than rounded into one.
What to do with the answer
- The tag is low but the pixels are plenty → re-tag it: 300 DPI for photographs, 600 DPI for line art and scans.
- The pixels are too few for the size you need → no tag helps. Re-scan, re-export from the original, or print smaller.
- Two values disagree → re-tag it here; both fields are written together, so the disagreement is resolved rather than moved.
How to check an image’s DPI
Step 1: Drop the file in
Drag a JPG or PNG onto the box above. Nothing is converted until you ask for it.
Step 2: Read the report
You get the declared density, where in the file it was found, the pixel dimensions, and a warning if two sources disagree.
Step 3: Compare against the paper you need
The panel converts pixels into a physical print size, so you can see immediately whether the file covers A4, a 10 × 15 photo, or a business card.
Frequently Asked Questions
How do I check the DPI of an image without installing anything?
Drop it on this page. The reader runs in the browser tab you already have open, and the file does not leave your device.
My file says “no density declared”. Is that bad?
Usually not. It is very common for screenshots and images exported for the web. Any program that prints it will apply its own default, which is why a print shop may ask you to state one explicitly.
Why is the DPI in Windows file properties different from what my editor shows?
They may be reading different fields of the same JPEG — Windows tends to report one, professional editors prefer the EXIF tags. When the two disagree, this page shows you both instead of picking one.
Does checking the DPI change my file?
No. Reading is a separate operation; a new file is produced only when you run a conversion, and the original on your disk is never modified either way.
Related Tools
- Convert an Image to 300 DPIRe-tag a JPG or PNG as 300 DPI without touching a single pixel — and see, before you send it, whether the file really covers the paper.
- Convert an Image to 600 DPISet a file to 600 DPI without re-encoding it — and find out first whether 600 is what your job actually needs.
- Image DPI Converter (72 to 300 DPI)Set the DPI your print shop asked for, and see the size the file will actually print at.