Grayscale Converter
Choose a JPEG, PNG, or WebP, select the grayscale method, and download a PNG locally.
JPEG, PNG, or WebP up to 20 MB.
Choose an image to begin.
A QUICK WALKTHROUGH
How to use this tool
- Choose one image up to 20 MB, 10,000 px per side, and 40 megapixels.
- Choose standard weighted luminance or simple average.
- Preview and download a transparent-capable PNG.
Two explicit methods
Standard weighted luminance approximates perceived brightness with coefficients 0.2126, 0.7152, and 0.0722. Simple average gives each RGB channel equal weight. Both preserve alpha.
Local output and limits
Processing uses browser Canvas and accepts JPEG, PNG, or WebP up to 20 MB, 10,000 pixels per side, and 40 megapixels. PNG download retains transparency; Canvas export removes source metadata and animation.
GOOD TO KNOW
Common questions
Is transparency preserved?
Yes. The PNG output keeps the source alpha channel.
Which method should I use?
Weighted luminance generally matches perceived brightness; simple average is a neutral channel average.
Is my image uploaded?
No. Decoding, conversion, preview, and download happen locally in your browser.