Change video speed online — speed up, slow down, or make slow-motion and timelapse video. Audio stays in pitch, no watermark.
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Changes video playback speed only.
Just changing an audio track? Use the Audio Speed Changer. Want to cut the clip down first? Try the Video Trimmer. Need a smaller file afterwards? Run it through the Video Compressor.
Upload a video, pick a speed, and download the retimed MP4
Most speed changes have nothing to do with the story and everything to do with time. A screen recording drags and you want it to move; an interview answer has to fit a 30-second cut; a two-hour build needs to land as a fifteen-second timelapse; a fast hand movement is impossible to follow until you slow it down. This tool does exactly one job well — it changes how fast a video plays, from a quarter speed (0.25×) up to four times speed (4×) — and it keeps the audio sounding right while it does.
Two clocks have to change together when you alter playback speed: the video timing and the audio timing. The picture is retimed with ffmpeg's setpts filter, which rewrites each frame's presentation timestamp. At 2× it multiplies every timestamp by one half (setpts=0.5*PTS) so frames are shown twice as fast; at 0.5× it doubles them (setpts=2*PTS) so each frame lingers. No frames are added or removed — the existing frames are simply shown closer together or further apart in time.
The audio is the part most quick tools get wrong. If you just play the samples faster — the way a tape machine speeds up when you spin it quicker — the pitch rises with the speed. A 2× voice becomes a squeaky chipmunk and a slowed voice turns into a low drone. To avoid that, this tool stretches the audio in time with ffmpeg's atempo filter, which changes duration without moving the pitch. The voice or music plays faster or slower but stays on the same notes, so it still sounds like a person talking rather than a cartoon.
atempo only accepts a factor between 0.5 and 2.0 in a single pass, so bigger changes are applied as a chain: 4× runs two 2.0 stages back to back (atempo=2,atempo=2) and 0.25× runs two 0.5 stages (atempo=0.5,atempo=0.5). You never see this — you just pick a speed — but it is why the pitch stays clean even at the extremes.
Speeding a clip up makes it shorter; slowing it down makes it longer. The size and duration limits below apply to the input you upload, not the output — so a 5-minute source slowed to 0.25× legitimately produces a 20-minute video. Here is what happens to a 5:00 clip:
| Speed | Effect | Output length |
|---|---|---|
| 0.25× | Slow motion | 20:00 |
| 0.5× | Slow motion | 10:00 |
| 1.5× | Faster | 3:20 |
| 2× | Faster | 2:30 |
| 4× | Timelapse | 1:15 |
This version retimes the frames you already have; it does not invent new in-between frames (there is no optical-flow or frame-interpolation step yet). For mild slow-motion that looks fine, but pushing footage shot at 25 or 30 fps down to 0.25× can look slightly choppy, because each original frame is simply held on screen longer. For buttery slow-motion, film at a high frame rate (60, 120 or 240 fps) and then slow that footage down.
At 2× and above the sped-up audio is rarely worth keeping — a timelapse with frantic chattering underneath helps no one — so you can switch on Remove audio to export a silent video. If your source has no audio track to begin with, the output is simply silent and the tool still works normally.
Without an account you can retime one video up to 100 MB and 5 minutes; a free account raises that to 200 MB and 10 minutes per file. The length cap keeps each run fast, because the video is re-encoded while you wait. Your files are processed securely, are never shared, and the retimed output is automatically deleted from storage after a short time — download it and keep your copy. No account is required to use the tool.
Upload your video, pick a speed — use a preset (0.25×, 0.5×, 1.5×, 2×, 4×) or type any value between 0.25× and 4× — and click Change Video Speed. Above 1× plays faster (and shortens the clip); below 1× plays slower for a slow-motion effect (and lengthens it). Download the retimed MP4 when it finishes.
No. The audio is time-stretched with ffmpeg's atempo filter, which changes the duration without changing the pitch — so a sped-up voice does not become a chipmunk and a slowed-down voice does not drone. It simply plays faster or slower at its natural pitch. If you would rather have no sound at all, switch on Remove audio.
Choose a speed below 1× — 0.5× plays at half speed, 0.25× at quarter speed. Because the tool retimes existing frames rather than generating new ones, footage shot at 25–30 fps can look slightly choppy at extreme slow speeds. For the smoothest slow-motion, record at a high frame rate (60 fps or more) and then slow it down here.
Pick a fast speed — 2× or 4× — to compress a long clip into a short one. A 5-minute clip at 4× becomes a 1:15 timelapse. At these speeds the audio rarely helps, so the tool suggests Remove audio to give you a clean silent timelapse you can score later.
You can go from 0.25× (quarter speed, four times longer) up to 4× (four times faster, a quarter of the length). Any value in between works too — type a custom number like 1.25× or 3× into the speed box. Leaving it at 1× does nothing, so the tool asks you to pick a different speed.
It depends on the direction. Speeding a clip up makes it shorter (2× halves the running time); slowing it down makes it longer (0.5× doubles it, 0.25× quadruples it). The upload limits apply to the video you put in, so slowing a 5-minute clip to 0.25× correctly produces a 20-minute output.
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