Change DPI of Image
Set 300 DPI without re-encoding the pixels — JPEG and PNG, whole batches at once, with no upload.
Only the density tag changes. Pixels are copied through untouched, so the picture looks identical and the file size barely moves — a bigger DPI number cannot add detail that was never there.
Everything runs locally in your browser. Nothing is uploaded to any server — close the tab and your files are gone.
How to use
Add your JPEG or PNG files
Drag in as many as you like, or click to browse. Each file is identified by its actual header bytes, so a mislabelled extension won’t slip through. Nothing is uploaded — your browser reads the files directly.
Choose the target DPI
Tap 300 for most print work, or type any value from 1 to 2400. One setting applies to the whole list, and changing it re-runs every file instantly.
Check the print size
Each row shows the pixel size and what it comes to on paper at the new DPI, in millimetres and inches. If that’s smaller than you need, the image needs more pixels — no DPI value can conjure them.
Download
Take files one at a time, or the whole batch as a ZIP. Each is saved as name-300dpi.jpg, so your originals stay exactly where they are.
Frequently asked questions
Does changing the DPI make my image sharper?
No. DPI is a note attached to the file saying how large one pixel should be printed — it never creates pixels. A 600 × 600 photo holds exactly 600 × 600 pixels of detail at 72 DPI and at 300 DPI alike; only the printed size changes, from about 212 mm across down to about 51 mm. Sharpness comes from having enough pixels in the first place.
My export is 72 DPI and the print shop asked for 300 — is changing it enough?
It is, as long as the image already has the pixels, and that is what the request usually comes down to. Do the arithmetic: pixels ÷ 300 × 25.4 gives millimetres. If a 3543 × 2362 image lands on the 300 × 200 mm you need, the file was print-ready all along and only the tag was wrong — which is exactly what this tool fixes. If the result comes out far too small, re-export the artwork at a larger pixel size instead.
Why is the new file almost exactly the same size?
Because the image data is copied through byte for byte. A JPEG usually changes by five bytes — the density unit and the two density values in its JFIF header — and a PNG grows by 21 bytes when it needs a new pHYs chunk. Nothing is decoded or re-compressed, so there is no generation loss even if you run the same file through repeatedly.
Why can I only change JPEG and PNG?
They are the two common formats with a standard place to record density: the JFIF and EXIF fields in JPEG, the pHYs chunk in PNG. WebP has no standard density field at all, so a print shop would have nothing to read, and inventing one would mean rebuilding the container. GIF has none either. On the vector side, PDF and SVG state physical size directly and don’t use DPI.
What happens if my JPEG has EXIF without resolution tags?
The EXIF block is left byte for byte as it was, and the DPI goes into the JFIF header, which print workflows read. Inserting a tag into an EXIF directory would shift every value offset stored behind it and quietly break the rest of the metadata, so this tool never does that. When EXIF already carries XResolution and YResolution, those are rewritten in place so the two headers never disagree.
Where does the DPI change actually happen?
In your browser, on your own machine. The file is read into memory, a handful of header bytes are rewritten, and the result is handed straight back to you as a download. There is no upload and no server copy — once the page has loaded, the conversion needs no network at all.