Inspect · read-only
Check the DPI of an image
Drop a file to see every resolution block inside it: JFIF, EXIF, PNG pHYs, the BMP header, TIFF tags. The report also shows pixel dimensions, conflicting values, and the largest clean print at your target DPI.
Batch inspector
No files yet
Checking never writes to a file. Set the target DPI and paper size to adjust the print verdict.
Drop images to inspect
JPEG · PNG · BMP · TIFF · up to 30 files · 100 MB each
Nothing is uploaded. Metadata is read and rewritten inside this tab.
01
What the report contains
The card reports the format, pixel dimensions, resolution blocks, print size and verdict.
Each file card reports the format, the pixel dimensions, and every resolution block the format can carry. A JPEG can hold two independent values, and a TIFF can hold a different value on every page. A file manager shows one number.
- Format and dimensions come from the file signature and the image header, not from the filename extension.
- Resolution blocks are listed by source, so you can see JFIF at 72 DPI next to EXIF at 300 DPI when both exist.
- The largest print is the pixel dimensions divided by your target DPI. It is a physical size, not a quality promise.
- The verdict compares the pixels you have with the paper size you chose, at the target DPI. It does not care what the embedded tag says.
02
Find DPI without this page
The same values, read with tools already on your machine.
Windows Explorer
Right-click the image, choose Properties, then the Details tab. The Image section shows horizontal and vertical resolution. Explorer presents a single pair of values and may show 96 DPI when no tag exists, so treat it as a quick check rather than a byte-level report.
macOS Preview
Open the file in Preview and choose Tools → Show Inspector (⌘I). The info pane reports image DPI alongside pixel dimensions. Finder's Get Info window shows dimensions but not resolution.
Command line
On macOS, sips can read the value. ImageMagick and ExifTool give more detail, including which block the number came from.
sips -g pixelWidth -g pixelHeight -g dpiWidth -g dpiHeight photo.jpg
identify -format "%wx%h px, %x x %y %U\n" photo.jpg
exiftool -XResolution -YResolution -ResolutionUnit -JFIF:XResolution photo.jpgsips reports 72 DPI as a fallback for files with no resolution block, so a value of 72 is not proof that a tag exists. Our checker tells the two apart and prints “Not embedded” when the file genuinely has no value.
03
When a file has no DPI
A file without a resolution tag is still valid.
A JPEG saved with the JFIF density unit set to 0 declares no physical resolution. A PNG without a pHYs chunk has none either. Plenty of perfectly good images fall into this category, especially screenshots, browser exports and images that passed through a messaging app.
When the tag is missing, layout software chooses a default, usually 72 or 96 DPI. That default determines the starting print size, not whether the image is sharp. Add a real value with the DPI converter when a lab or a submission form asks for one.
| Format | Where DPI lives | What the checker reports | Common gotcha |
|---|---|---|---|
| JPEG | JFIF density and EXIF tags | Both values shown separately | Unit 0 in JFIF means no density is stored. |
| PNG | pHYs chunk | Pixels per metre, converted to DPI | Most screenshots and web exports have no pHYs at all. |
| BMP | DIB header, bytes 38 and 42 | Pixels per metre | Older 12-byte headers may omit the fields. |
| TIFF | IFD tags 282, 283, 296 | Every page is inspected | A page can carry a different resolution from the next. |
| WebP | EXIF chunk | Read when present | Lossy WebP often drops metadata. |
| GIF | No DPI field | No reading | The format has no place to store resolution. |
04
Reading the verdict
The chip reports how the pixels fit the paper size you selected.
The chip on each file card summarises whether the image can fill the selected paper size at the target DPI. Clears this size means the pixel dimensions meet the requirement, even if the embedded tag currently says something else. Pixels are thin means the print will resolve between roughly 150 and 300 DPI: usable for a poster viewed from a metre away, soft for a hand-held print.
Pixels fall short means the effective resolution is under 150 DPI. At that point, changing the tag will not help. Either print smaller, find a larger original, or accept an interpolated enlargement. The guide lays out those three options with the trade-offs.
Questions people ask
Practical answers about the numbers the checker reports.
How do I check the DPI of an image on Windows?
Right-click the file, open Properties, and look under the Details tab in the Image section for Horizontal resolution and Vertical resolution. Windows shows one pair of values and assumes 96 DPI when the file has no tag, so it can hide a missing or conflicting resolution block.
Why does the checker say DPI is not embedded?
The file has no resolution block that applies to it. A JPEG can be saved with the JFIF density unit set to 0, which means "aspect ratio only". A PNG only carries DPI in a pHYs chunk, and many web exporters never write one. The image is still valid; software simply falls back to 72 or 96 DPI when placing it.
Why do two DPI values appear in the same file?
JPEG can carry both a JFIF density block and EXIF resolution tags. Different applications read different blocks, so a file edited in two programs can report 72 DPI in one place and 300 DPI in another. The checker lists both and flags the conflict. Our converter writes one value to both.
Does checking an image upload it anywhere?
No. The file is opened with the browser File API and parsed locally. There is no network request carrying your image. You can disconnect from the internet after the page loads and the checker still works.
Is a 72 DPI image bad?
No. 72 DPI is a print instruction, not a quality score. A 3000 pixel wide image tagged 72 DPI still holds 3000 pixels and is sharp at 10 inches when set to 300 DPI. The pixel count against the intended print size decides how it looks.
Can I check the DPI of a PDF or HEIC file?
HEIC and AVIF files are read for their stored pixel dimensions and resolution where the container exposes it. PDF is detected but not measured, because PDF resolution depends on how each page is rendered rather than on one file-wide tag.