Convert Image to Grayscale Online Free
Turn any color JPG, PNG, or WebP image into black and white instantly in your browser. Free, no signup, files never leave your device.
🔒 Your file never leaves your browser. All processing is done locally.
How to Convert an Image to Grayscale
- 1
Upload your image
Click the upload zone or drag and drop a JPG, PNG, or WebP image. Your file stays on your device.
- 2
Convert to grayscale
Click "Convert to Grayscale". The conversion runs instantly in your browser using the HTML Canvas API and the standard luminance formula.
- 3
Download the result
Preview the before and after images side by side, then click Download to save the grayscale version.
A grayscale image represents each pixel as a single shade of grey — from pure black to pure white — with no colour information. Grayscale images are used in photography, document scanning, printing, and as a preprocessing step in computer vision and machine learning tasks.
How it works: The tool draws your image onto an HTML Canvas and applies the standard ITU-R BT.601 luminance formula to every pixel: L = 0.299 × R + 0.587 × G + 0.114 × B. This formula weights green most heavily because the human eye is most sensitive to green light, producing a perceptually accurate grayscale result — not just an average of the three channels.
When to use grayscale: Convert to grayscale when preparing images for black-and-white printing, creating a classic photographic look, reducing complexity before OCR or edge detection, or producing document scans with smaller storage requirements.
Next steps: After converting, you might want to compress the image to reduce file size further, or crop it to focus on a specific area.