Change video speed

Every frame of a video carries a timestamp saying when it should appear. Speeding up squeezes those timestamps together; slowing down spreads them apart. At 2× a 10-minute video becomes 5 minutes; at 0.5× it becomes 20. The pictures themselves don't change – only how quickly they follow one another.

The tool shows the new length up front, and the finished video matches it (typically within a frame or two). The output is H.264 MP4, which every phone, computer and social network plays.

• Keep the pitch (recommended): the sound speeds up or slows down with the video, but its pitch stays the same – no chipmunk voice, no deep, dragging voice either. We use our own WSOLA-style time-stretching algorithm: it slices the audio into short, overlapping pieces and reassembles them so the waveforms line up. For speech it's excellent between 0.5× and 2×; with music or extreme speeds you may hear a slight echo-like artifact.
• Tape style: like a tape spinning faster or slower – higher when sped up, deeper when slowed down. Fun as an effect.
• No audio: when you'll add music later, or the sound doesn't matter (a timelapse, say).

If you only want to change the speed of audio, without video, use change audio speed.

Slowing down doesn't create new frames: slow a 30 fps video to 0.5× and you get 15 frames per second; at 0.25×, only 7.5. That already looks choppy. Truly smooth slow motion has to be recorded at a high frame rate in the first place – most phones have a 120 or 240 fps slo-mo mode, and footage like that stays fluid even at 0.25×.

The tool warns you when too few frames per second would be left after slowing down, so you know what to expect. We don't promise “invented” in-between frames (frame interpolation) – that would need an AI model.

Speeding up packs frames closer together: a 30 fps video at 4× would become 120 fps. Most players and social networks can't use that, so we keep at most 60 frames per second and skip the rest. The file doesn't balloon for nothing and plays smoothly everywhere.

Typical speed-ups:

• Only want to speed up one part? Cut it out with the video trimmer, speed it up, then put it back with merge videos.
• For Reels and TikTok: a 90-second raw clip at 1.5× drops under 60 seconds and the speech stays clear.
• Custom speed: type any value from 0.25 to 4, for example 1.1 for a barely noticeable speed-up that still saves time.
• File too big? If the result is larger than you'd like, the video compressor shrinks it to a target size.

Processing uses the browser's built-in video encoder (WebCodecs) in Chrome, Edge and recent Safari and Firefox. Your video isn't uploaded: decoding the frames, rewriting the timestamps, stretching the audio and building the MP4 all happen on your own device. No watermark, no sign-up.