Turn any photo black and white with a choice of four conversion methods, keep a hint of colour if you like, and convert a whole folder in one go.
Replaces the colour of every pixel with a single brightness value, then blends that result back with the original by the amount you set. Four methods decide how red, green and blue are weighed. Luminance uses the broadcast weights 0.299, 0.587 and 0.114, so a bright green and a bright blue that look different to the eye also come out different in grey. Average treats the three channels equally. Lightness takes the midpoint between the strongest and weakest channel. Red filter mimics a red glass filter on a film camera and pulls most of its brightness from the red channel.
A 3000 × 2000 photo of a red barn against a blue sky converted with Luminance gives the barn a mid grey of about 120 and the sky a light grey of about 180, so the two read as similar tones. The same photo with Red filter makes the barn about 200 and the sky about 70, a classic high-contrast landscape where the sky goes almost black behind white clouds. At Amount 60 with Luminance the barn keeps a faint dusty red, a look that suits documentary-style edits. The file size hardly moves: 2.1 MB in, about 2.0 MB out as JPEG at quality 92.
Use it for portraits where colour distracts, for printing on a mono laser printer, for consistent product thumbnails, or as the first step before Change Contrast to build a punchy black-and-white edit. If you want a warm tint rather than neutral grey, Sepia Effect gets there in one step. Do not convert a screenshot or a chart that relies on colour to tell lines apart; Luminance can map two different colours to nearly the same grey, and Invert Image Colors or a contrast change may serve you better there.
Amount at 100 removes all colour; lower values keep a proportional wash of the original. Method only changes how brightness is computed, not how much colour is removed, so compare them with Amount at 100 first. Output Same keeps a PNG as PNG and a JPEG as JPEG; pick WebP when the result is for a website and you want a smaller file. Batch mode applies one setting to every file and gives you a single ZIP.
Which method should I pick? Luminance for almost everything; it matches how the eye judges brightness, so faces and foliage keep their natural tone. Try Red filter on landscapes with blue sky, which goes dramatically dark while clouds stay bright.
Does black and white make the file smaller? Not by itself. A JPEG stores brightness and colour separately and the colour part was already small. If you need a smaller file, lower the quality in Output or run Image Compressor afterwards.
Can I keep a little colour? Yes. Set Amount to 60 or 70 and the picture keeps a faint wash of its original colours, a look that works well for muted, vintage-style photos. Sepia Effect does a similar job with a warm brown tint instead.
Is the picture uploaded anywhere? No. Every pixel is converted inside your browser with the canvas API and the file never leaves your computer. Batch mode works the same way, one file after another.