Grayscale Image Converter: what it does
Convert any image to grayscale and choose exactly how it is calculated. Luminance (Rec. 709) weights green most and blue least, the way our eyes see brightness, and is the right choice for most photos and screens. Luma (Rec. 601) is the older video standard, used by many image editors. Average simply takes (R + G + B) ÷ 3, and Lightness takes the midpoint of the brightest and darkest channel. The image keeps its full size and any transparency, and it is converted in your browser without being uploaded.
How to use it
- Drop a photo into the box, paste it with Ctrl+V, or tap to choose one from your phone.
- See the effect straight away. The thumbnails show every other effect on your photo too.
- Adjust the settings, and hold “Hold to compare” to see the original.
- Download at full resolution as JPG, PNG or WebP.
Tips
- Luminance (Rec. 709) gives the most natural result for photos.
- Average makes blues look too bright and greens too dark; it is mainly useful when a course or a tool asks for that formula.
- Converting for a form or an exam portal that wants a “grayscale image”? Save as JPG to keep the file small.
- Transparent PNGs stay transparent if you save as PNG or WebP.
Frequently asked questions
Which grayscale formula is the best?
For photos, luminance (Rec. 709: 0.2126 R + 0.7152 G + 0.0722 B), because it matches how bright colours look to people. Rec. 601 (0.299 R + 0.587 G + 0.114 B) is very close and is what many editors use.
Is the file saved as a single-channel grayscale image?
Browsers save images in RGB, so the file has three identical channels. It looks and prints exactly as grayscale; if a system needs a true 8-bit single-channel file, convert it in a desktop editor afterwards.
Is my image uploaded?
No. The conversion is done by your browser on your own device.