Video Speed Changer

The new length is the original length divided by the speed. A one-minute video becomes 30 seconds at 2× and two minutes at 0.5×.

Simply playing sound faster raises its pitch, which makes voices sound like cartoons, and slowing it down makes them deep. With Keep the pitch the tool uses a time-stretch method (WSOLA) that removes or repeats tiny slices of sound so the speed changes but the pitch does not. It works best between about 0.5× and 2×; at the extremes some echo or roughness is normal. Choose Change pitch with speed for the classic chipmunk or slow-motion effect, or Remove sound for a silent clip.

When speeding up, the video keeps its original frame rate by skipping frames, so a 30 frames-per-second video stays at 30 frames per second and the file does not grow. When slowing down, each frame is shown for longer. Slow motion therefore looks smoothest with videos filmed at a high frame rate, such as the 120 or 240 fps slow-motion mode of many phones.

The video is re-encoded at high quality with your browser's built-in encoder, using H.264 and AAC in an MP4 file where available. Long or 4K videos take some time, depending on your device; you can follow the progress and cancel at any time. Nothing is uploaded: the whole job runs on your own computer or phone.

Speeding up turns long, slow processes into short clips people will actually watch: a drawing, a cooking recipe, a room makeover, a build, a drive or a sunset. Recorded lectures, webinars and meetings are easier to review at 1.25× or 1.5× with the pitch kept natural. Slowing down is useful to study a golf swing, a cricket shot, a dance step or a fast trick, or to make a dramatic moment last longer. For social media, 2× clips of everyday tasks and 0.5× clips of splashes, jumps and laughs are popular. Combine the tool with the Video Cutter to change the speed of just one part: cut it out, change its speed here, and join the parts again with the Video Merger.