Can this measure my mouse DPI?

No. Mouse DPI is how far the pointer moves per inch of hand movement, a sensor setting that has nothing to do with picture files. This page only reads image files.

Does it check the DPI of a PDF?

No, PDF files are not read. If the PDF came from a scan, check the original JPG or PNG from the scanner, or export the page as an image and check that.

Why does my iPhone photo say no DPI is stored?

The checker reads density from JPG, PNG and TIFF only. HEIC, WebP and AVIF files are opened for their pixel size, but no DPI is read from them, so the report shows none. Convert the photo to JPG and write a DPI into it if a form needs one.

Is a higher DPI number always better?

Not by itself. Changing 72 to 300 in the header adds no detail; it only makes the print smaller. What matters is whether the pixel size, at the DPI the form names, gives the centimetres it asks for.

Does checking change or upload my file?

Neither. The file is read inside your browser, nothing is rewritten, and there is no download button because there is nothing new to save.

DPI Checker: See an Image’s DPI and Print Size

A DPI figure is a single number tucked into the header of a JPG, PNG or TIFF. It does not alter a single pixel; it only tells printers and layout programs how many of those pixels to squeeze into each inch of paper. Windows and most phones hide it several menus deep, so it is hard to answer a simple question such as “is this scan really 200 DPI?” before an application deadline.

This checker opens the file, reads that number and the true width and height in pixels, and turns the pair into a physical size in centimetres and inches. It also shows how large the same pixels would print at 300 DPI, the usual quality bar for photographs. Your file stays exactly as it was; there is no new copy to save.

A black-and-white close-up of the edge of a thick stack of printed paper sheets on a plain white surface

How to use it

Pick the scan, photo or signature you are about to submit, in the same format you will upload.
Tap Check DPI. The report appears in a second or two.
Read the two boxes: the pixel size with file weight, and the DPI the file declares, or “No DPI stored”.
Compare the print-size rows with the centimetres in your instructions. If only the DPI value is wrong, rewrite it with the Convert DPI tool; if the pixel count is wrong, resize instead.

How to read the report

Print size is simple arithmetic: pixels ÷ DPI = inches, and inches × 2.54 = centimetres. A 600 × 600 pixel file marked 300 DPI covers 2 × 2 inches (5.08 cm each way); mark the very same file 150 DPI and it covers 4 × 4 inches, although nothing on screen looks any different. That is why the pixel count is the figure that limits sharpness, while the DPI only decides how the printer spreads those pixels out.

“No DPI stored” is common and harmless on its own. WebP, HEIC, AVIF, GIF and BMP files show it here, as do screenshots and pictures saved by many apps; software then assumes 72 or 96. A value of 72 on a phone photo is also routine: cameras write it by habit, and it says nothing about quality. For JPGs the tool reads the JFIF header first and falls back to the EXIF resolution, so the number matches what most editors display.

Checking a file against a “200 DPI” instruction

Several recruitment notices pair DPI with pixels and centimetres in one line. IBPS (PO/MT, CSA, SO and RRB), SBI (PO and Junior Associates), NABARD Grade A and MIDC ask for the left thumb impression at 240 x 240 pixels in 200 DPI (preferred) i.e 3 cm * 3 cm, and the handwritten declaration at 800 x 400 pixels in 200 DPI (preferred) i.e. 10 cm * 5 cm. A file that passes shows 240 × 240 (or 800 × 400) in the pixel box, 200 DPI in the second box, and 3.05 × 3.05 cm (or 10.16 × 5.08 cm) in the first print-size row.

The UPPSC One Time Registration instructions give only centimetres plus a scan at 200 DPI: photo 5 cm width x 6 cm height, signature 6 cm width x 3 cm height. At 200 DPI those boxes work out to about 394 × 472 pixels and 472 × 236 pixels. If the report shows 200 DPI and the print size is close to 5 × 6 cm or 6 × 3 cm, the scan is in line; if it shows a different DPI but the right pixel count, only the stored number needs rewriting.

Frequently asked questions

Can this measure my mouse DPI?: No. Mouse DPI is how far the pointer moves per inch of hand movement, a sensor setting that has nothing to do with picture files. This page only reads image files.
Does it check the DPI of a PDF?: No, PDF files are not read. If the PDF came from a scan, check the original JPG or PNG from the scanner, or export the page as an image and check that.
Why does my iPhone photo say no DPI is stored?: The checker reads density from JPG, PNG and TIFF only. HEIC, WebP and AVIF files are opened for their pixel size, but no DPI is read from them, so the report shows none. Convert the photo to JPG and write a DPI into it if a form needs one.
Is a higher DPI number always better?: Not by itself. Changing 72 to 300 in the header adds no detail; it only makes the print smaller. What matters is whether the pixel size, at the DPI the form names, gives the centimetres it asks for.
Does checking change or upload my file?: Neither. The file is read inside your browser, nothing is rewritten, and there is no download button because there is nothing new to save.