Black and white video
Take the color out of a clip. The audio is copied across untouched.
Your file
Drop a file here, or click to choose
It stays on this device. Nothing is sent anywhere.
Settings
Not all monochrome looks the same
Removing color is a decision about which grays the colors become. A flat desaturation makes a red jumper and a green hedge land on nearly the same gray, which is why naive black and white footage looks muddy. Raising the contrast separates them again and gives the picture some snap.
Because only the picture is touched, the sound track is copied through byte for byte and loses nothing.
Why this costs a re-encode when the image version does not
Draining the color out of a still is a single operation on a single picture. Doing it to video means decoding every frame, filtering it, and encoding it again, which is why there is a quality slider on this page and none on the black and white image tool. That slider is -crf: 23 is the h.264 default, lower numbers keep more detail and produce larger files, and anything past about 30 starts to look soft.
There is a small consolation. Monochrome footage compresses better than color, because the two chroma planes are carrying almost no information once they are flattened. At the same CRF, a black and white export is usually somewhat smaller than the color original, though not dramatically so, since the luma plane is where most of the bytes always were.
Grading before you desaturate
Order matters more than people expect. Contrast and brightness here are applied through the eq filter in the same pass as the desaturation, so you are shaping the gray image rather than correcting a color one and hoping. That is the right way round: what you are judging on screen is exactly what gets encoded.
Footage shot flat, on a phone in bright sun or on a camera with a log profile, almost always needs contrast above 100 to stop looking washed out. Footage that was already contrasty, like anything shot at night with hard lighting, needs it left alone or lowered, since crushing the shadows in black and white loses detail with nothing to hint at what was there.
If you want a black and white section rather than a whole clip, the editor applies effects per piece of the timeline, so one shot can be monochrome inside an otherwise color edit.
Common questions
Can I get the color back afterwards?
Not from the output. The color information is discarded, so keep your original.
Does this make the file smaller?
Usually a little, since there is less chroma information to encode, but the saving is modest.