Convert images to greyscale
For documents, printing, and forms that ask for a monochrome scan. The conversion uses the Rec. 709 luminance weights, so greens do not come out unnaturally dark.
- Runs entirely in your browser
- Works offline
- No upload
- No sign-up
- No watermark
Loading the tool…
How it works
- Drop your images.
- Greyscale is already ticked; add a resize or a format change if you want.
- Convert and download.
Why nothing is uploaded
Every operation on this page is done by code running inside your browser tab, using the same engine that renders web pages. The file is read from disk into your tab’s memory, transformed there, and written back out as a download. It is never sent anywhere — not to us, not to a third party.
Verify it yourself
- Open your browser’s developer tools (F12) and select the Network tab.
- Load your file and run the tool.
- The only requests you will see are the tool’s own code and, once cached, none at all.
Frequently asked questions
What is wrong with averaging the three channels?
The eye is far more sensitive to green than to blue. A flat (R+G+B)/3 average makes foliage and skin look muddy. Weighting them 0.2126 / 0.7152 / 0.0722 — the Rec. 709 luminance formula — matches perceived brightness.
Does the file get smaller?
Usually yes, because the colour channels carry almost no information afterwards. If you also need it small, tick “Squeeze harder” to run MozJPEG or OxiPNG over the result.
Are the images uploaded to convert them?
No. The image is decoded by your browser, redrawn on a canvas and re-encoded there. Load the page, switch your connection off and the conversion still works — that is the proof.
Is there a size or batch limit?
None that we impose. Drop a hundred files if you like; they are processed one after another with a progress bar, and the ceiling is your device’s memory.
What happens to EXIF and GPS data?
It is dropped by default, which is usually what you want before sending a photo to anyone. Tick “Keep EXIF” if you need the capture date and camera preserved in a JPEG output.