Convert images to greyscale
For documents, printing, and forms that ask for a monochrome scan. The conversion uses the standard brightness formula (Rec. 709), 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 fetch the tool’s own code — and, for a few heavy tools, their open-source engine from a public CDN — plus one small page-view ping to loreatec.jp (page address and title, nothing more). None of them carry your file.
Frequently asked questions
What is wrong with simply averaging the colours?
The eye is far more sensitive to green than to blue. A plain average of red, green and blue makes leaves and skin look muddy. Weighting them 0.2126 / 0.7152 / 0.0722 (the Rec. 709 brightness formula) matches how bright things actually look.
Does the file get smaller?
Usually yes, because the colour information is gone. If you also need it small, tick “Compress harder” to run the stronger compressors over the result.
Are the images uploaded to convert them?
No. Your browser opens the image, redraws it and saves it in the new format, all on your device. 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 only limit is your device’s memory.
What happens to the hidden photo data (EXIF, GPS location)?
It is removed by default, which is usually what you want before sending a photo to anyone. Tick “Keep EXIF” if you need the date and camera details kept in a JPEG output.