How a color image becomes grayscale
A color image stores three values for each pixel: red, green and blue. Turning it into grayscale means replacing those three numbers with a single brightness value and using that same value for all three channels.
The simplest approach is to average the three channels, but that looks wrong because the eye does not see them equally. Green looks brightest to us, red is in the middle, and blue looks darkest. This tool uses a weighted formula that reflects that: 29.9 percent red, 58.7 percent green and 11.4 percent blue. A pure green pixel therefore ends up much lighter than a pure blue one, which is how a black and white photo should behave.
The pixel dimensions stay exactly the same, and only the color information is removed.
When a grayscale version is useful
Photographers often convert to black and white to give a picture a timeless look, or to rescue a shot with awkward color casts. Designers use grayscale copies when checking whether an interface or poster still has enough contrast without relying on color.
It is also practical for documents. A grayscale scan or screenshot is more suitable for printing on a black and white printer, and the result avoids surprise tones from color-only differences. If you plan to shrink the picture afterward, you can resize it with the image resizer once the conversion is done.
Grayscale is a one-way change. The color information is discarded in the output file, so keep your original if you may want the colors back.
How to convert an image to grayscale
- Drag an image onto the upload area, or click it to browse for a file.
- Your original is shown on the left, with its file name, size and dimensions underneath.
- Click Convert to grayscale. There are no sliders or settings for this tool.
- The black and white result appears on the right, along with a comparison of file sizes.
- Click Download to save it. The file is a PNG named after the original with "-grayscale" added, such as
holiday-grayscale.png. - Use Start over to load a different image.
The conversion happens locally in your browser, so the picture is not sent to a server.
Things to keep in mind
The output is always a PNG, even if you started with a JPG. PNG is lossless, so a converted photo can be noticeably larger than the source. If you need a smaller file, pass the result through the image compressor.
There is no contrast, brightness or tint control here. If the converted image looks flat, that usually means the original relied on color differences, such as red text on a green background, which look similar once color is removed.
Transparent areas of a PNG keep their transparency, because only the color channels are changed. Very large images need a moment to process since every pixel is rewritten.