Change image DPI · set it to 300
DPI 72–600, pixels untouched (1–2400 in the full editor). Local processing, nothing uploaded.
The print shop asks for 300 DPI and what you have is a photo from a phone — and nine times out of ten that doesn't mean reshooting it: DPI is just a number stored in the file. It says how large the image should print, not how much detail it holds.
First, what DPI actually is: it has nothing to do with sharpness. It is one number written into the file that tells a printer how many pixels to put in each inch, and so decides how big the print comes out. Physical size = pixels ÷ DPI — a 3000-pixel-wide image is 10 inches at 300 dpi and 41.7 inches at 72 dpi, with exactly the same pixels. This page simply gives you no “Resample” option: changing the DPI never touches a pixel, and the slider runs from 72 to 600 (the range photo labs and presses actually use, 300 by default). What you download is a PNG, with that number in its pHYs chunk. For the full 1 to 2400 range, or to write JFIF density into a JPG and change the pixel size while you are at it, press “Pro editor” for the full editor: the menu Image > Image Size… has the “Resample” dropdown right there (it appears together with “Scale content (Image Size)”, which is already ticked when you open it from here — just keep it ticked).
Key features
DPI 72–600
72 for the web, 150 for everyday printing, 300 for press, 600 for fine work.
Pixels untouched
This page gives you no “Resample” option at all: the pixels never change, only that one number written into the file.
Really written into the file
This page writes it into the PNG pHYs chunk, which print software reads; to write it into a JPG's JFIF density field, export a JPG from the full editor.
Runs locally
The image is never uploaded. Close the tab and nothing is left.
How to use
- 1 Add the imageDrag it into the box, or press Ctrl+V to paste.
- 2 Drag the DPI slider72 to 600, 300 by default — 300 is exactly what print shops ask for.
- 3 Not a single pixel changesThis page only rewrites that one number in the file; it never resamples. However many pixels go in, the same number come out. To change the pixel size itself, use the “Resize Image” page.
- 4 Download the PNGThe DPI is written into the PNG's pHYs chunk, which Photoshop and print-shop software both read. This page only makes PNGs — WebP simply has no such field.
FAQ
- Does changing DPI make the image sharper?
- No. This page gives you no “Resample” option at all, so the pixels never change — the DPI is just one number written into the file. Whether an image looks sharp depends on how many pixels it has, and has nothing to do with that number; changing it cannot conjure up detail.
- The print shop wants 300dpi — what do I do?
- First check whether you have the pixels: pixels needed = physical size in inches × 300. Printing 10×15 cm (about 3.94×5.91 in) needs roughly 1181×1772 pixels. If you have them, set DPI to 300 and you are done. If you do not, changing the number achieves nothing — you need a larger original.
- Why does my exported WebP have no DPI?
- WebP has no general resolution field. PNG has the pHYs chunk and JPG has the JFIF density field; WebP has no equivalent, so there is nowhere to write it. This page outputs PNG; for a JPG that carries a DPI, export a JPG from the full editor.
- Is it free? Is my image uploaded?
- Free, no sign-up, no usage limit. Nothing is uploaded either — it all runs in your own browser.
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