Grayscale Converter
Grayscale Converter converts an uploaded image into a black-and-white grayscale version directly in your browser.
Choose a luminance-weighted conversion for perceptual brightness or an average RGB conversion for a simple channel-equal result, then preview and download the converted image.
Choose an image and grayscale mode
JPG, JPEG, JFIF, PNG, WebP, AVIF, and BMP images up to 50 MB.
Best for screenshots, graphics, text, and transparency.
Grayscale result
Before/after preview, dimensions, format, and download.
No image selected
Upload an image to preview the original and create a grayscale output.
Supported image types
The tool converts browser-decodable still images and exports a new JPEG, PNG, or WebP file. Animated images are treated as a single decoded frame by browser image decoding.
How to Convert an Image to Grayscale
Upload and Preview
Use the upload drop zone for JPG, PNG, WebP, AVIF, BMP, and other browser-decodable still image files. The original image and converted grayscale image appear side by side so you can verify the result before downloading.
- Keep file processing local by decoding the selected File or Blob in the browser.
- Show image dimensions, input format, and output format after upload.
- Preserve the alpha channel so transparent PNG and WebP artwork keeps its transparency.
Choose a Grayscale Method
The default is designed to be luminance-weighted grayscale because green contributes more to perceived brightness than red or blue in standard RGB video and web color workflows. An average mode is still useful when users want a straightforward mathematical average of the red, green, and blue channels.
- Luminance mode: set red, green, and blue to 0.2126R + 0.7152G + 0.0722B for each pixel.
- Average mode: set red, green, and blue to (R + G + B) / 3 for each pixel.
- Keep alpha unchanged and clamp output channel values to the 0-255 byte range.
Download the Output
Export the processed canvas as a downloadable image. PNG is the safest default for screenshots and transparent artwork, while JPEG and WebP are available for photos and modern web output.
- Use a filename such as original-name-grayscale.png by default.
- Display output size after export so users can compare it with the original file.
- Warn when a browser cannot decode the selected image type instead of attempting a server fallback.
Privacy and Limits
The uploaded image is processed locally with Canvas pixel APIs. Large images can consume substantial memory because the browser stores RGBA pixel data, so oversized files are rejected before conversion.
- Do not upload image bytes for conversion, preview, or download generation.
- Use the shared access and paywall flow consistently with other image tools.
- Release object URLs and temporary canvas references after replacement or reset to avoid avoidable memory growth.
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