Increase the DPI of an image

DPI alone adds no detail. It changes how software labels the print size; it changes nothing in the picture.

The DPI panel, at 300, on “tag only”. The page reads the density your file already states (from its JFIF, Exif or pHYs header) and shows it before you change anything.

Only the label moves. To print 12 × 8 in at 300 ppi you need 3600 × 2400 pixels — choose “Enlarge to a print size” and the 12 × 8 in sheet, and the bench enlarges ×2 and writes 300 dpi into the result.

• It cannot add detail.A tag is metadata. A sharper print needs a sharper source; more pixels only meet the lab's density without its own resampling.
• WebP has no density field.A WebP or HEIC is saved as PNG with the tag, at the same pixels.
• A cropped picture is re-encoded.Once a crop is applied the original bytes no longer match the picture, so the tag-only path saves a lossless PNG instead.

Does 300 DPI make the photo sharper?

No. DPI in a file is a label: it tells software how many pixels to lay along an inch when it prints. Changing it from 72 to 300 changes the size the picture says it prints at, and nothing in the picture. Only more pixels let a lab print bigger at the same density — that is the second option on this page, and it is an enlargement, not a tag.

Is my JPEG re-compressed?

Not on the tag-only path. The file's own bytes are copied and only the density fields in its header are rewritten (the JFIF segment for a JPEG, the pHYs chunk for a PNG; an Exif resolution, if the file has one, is set to match). After the save both files are decoded in this tab and the SHA-256 of their pixels is shown, so you can see they are identical.

Why can't WebP have DPI?

WebP has no standard field for density. A WebP, HEIC or other file opened here is saved as a PNG at the same pixels with the tag — a lossless re-encode — and the pixel hashes are shown for that too.

What does the lab actually need?

Enough pixels for the paper at its density: a 6 × 4 in print at 300 ppi needs 1800 × 1200 pixels. A lab fits whatever it receives to the paper, whatever the tag says. The tag matters for software that lays out pages, and for forms that check it.

How do I know the tag was written?

After the save the density is parsed back out of the saved file and shown — for example “300 × 300 dpi (JFIF) — read back from the saved file”.

• Enlarge for printA conservative 2× opening state with the resulting print dimensions explained before export.
• Enlarge a scanned photoScan DPI and paper size set the factor; clean-up Light, density written into the file.
• Increase image resolutionType the exact width, height or long edge; the bench shows the factor that results and whether it fits.
• DPI is a labelWhat the DPI in a file changes (the printed size label) and what it does not (the picture).