Video Speed Control for Slow Motion or Fast Cuts

Q: Why does my slow-motion clip look jerky?

With Duplicate frames, a 30 fps clip at 0.25x shows every real frame four times, so movement jumps in steps. Switch to Frame blend or Motion interpolation, pick a less extreme speed, or start from footage recorded at a higher frame rate.

Speed up or slow down a video online, from 0.1x to 10x

Speed up or slow down a video from 0.1x to 10x and choose whether to preserve the audio pitch. A 20-second clip played at 2x lasts about 10 seconds; at 0.5x it lasts about 40 seconds. Frame interpolation changes how slower motion is rendered. Preview the movement and listen to the audio before exporting, since extreme changes can introduce visible or audible artifacts.

Cost: Free to use. File size and usage limits apply.

Example: play a clip twice as fast

Input: 20-second video
Setting: Speed 2x
Output: About 10 seconds of video

This is a timing example. Check the audio pitch and motion with your chosen settings.

How to change the speed of a video

Upload one video
Click Upload a video to change speed or drop a file onto the preview. MP4, MOV, MKV, WebM, AVI, M4V, MPEG and OGV files up to 200 MB work. Videos you used in other tools are listed under Uploads.
Set the speed
Click one of the presets from 0.25x to 4x, or use the slider or number field for any value from 0.1x to 10x. Values above 1x speed the clip up, values below 1x slow it down.
Choose audio and slow-motion handling
Leave Keep pitch on if people speak in the clip. Below 1x a Slow-motion method picker appears: it decides how the extra frames of a slower video are filled in.
Check the timing
Press Play to watch the clip at the chosen rate. The Output projection card shows the new Output length and a rough Estimated render time for the selected method.
Render and download
Click Change speed. The result replaces the preview: Download saves it and Continue editing lets you try other settings. The result also stays under Uploads for other tools.

Settings explained

Play the preview to hear and see the new rate: it follows the chosen speed and the Keep pitch setting. The slow-motion method creates new frames on the server, so its effect is visible in the rendered result.

Playback speed: The factor by which the clip plays faster or slower: 2x halves the running time, 0.5x doubles it. The range is 0.1x to 10x. At exactly 1x the timing stays the same, but the file is still re-encoded.
Keep pitch: On by default. The audio is time-stretched so voices keep their normal pitch and the sound ends exactly with the picture. At extreme factors stretched speech can sound choppy or smeared. Switched off, the sound behaves like a tape played faster or slower: higher when sped up, deeper when slowed down. In both modes the sound keeps pace with the picture.
Duplicate frames: The default slow-motion method. Source frames are repeated to fill the longer running time; at 0.5x a 30 fps clip shows every frame twice. It renders fastest and never invents detail, but the slower the speed, the more visibly movement advances in steps.
Frame blend: Fills the gaps by cross-fading neighboring frames. Motion looks softer, but fast objects leave faint double images (ghosting). Takes longer than Duplicate frames.
Motion interpolation: Estimates how things move between two frames and draws new frames in between. Smoothest for steady pans and simple movement, but scene cuts, overlapping objects and fast-moving hands can warp. The slowest of the three methods.

What happens to the frames: a worked example

Take a 12-second phone clip at 30 fps, which contains 360 frames. At 3x the result lasts 4 seconds and still runs at 30 fps, so every third original frame is kept. Nothing has to be invented, which is why the Slow-motion method picker is hidden at 1x and above.

At 0.5x the result lasts 24 seconds and needs 720 frames, but only 360 of them exist. Duplicate frames shows each one twice; Frame blend and Motion interpolation calculate the other 360. At 0.25x the clip runs 48 seconds and three out of every four frames must be filled in. That is where the difference between the methods is easiest to see.

When the speed changes, the output frame rate follows the source and is capped at 60 fps. That makes high-frame-rate footage the best starting point for slow motion: a clip recorded at 120 fps that plays at normal speed can be slowed to 0.5x and still consist only of real frames at 60 fps.

Which speed for which job

Tutorials and screen recordings: 1.25x to 2x

Keep pitch on so narration stays understandable. Screen content changes little between frames, so skipped frames are hard to notice.

Fast motion from normal footage: 4x to 10x

Enter values above 4x in the number field or use the slider. At 10x, a 5-minute walk or build becomes 30 seconds. The soundtrack is always kept; if it is only noise at this speed, remove it afterwards with Mute Video.

Action replays: 0.5x

Use Frame blend for busy scenes and Motion interpolation for steady camera pans. Check fast edges in the result for trails or warping.

Short loops and GIFs

Change the speed here first, then play the clip backwards with Reverse Video or turn it into an animation with Video to GIF.

Formats and limits

Speed range: 0.1x to 10x; presets 0.25x, 0.5x, 0.75x, 1x, 1.25x, 1.5x, 2x and 4x
Input formats: MP4, MOV, MKV, WebM, AVI, M4V, MPEG/MPG, OGV
Output format: Same container as the upload. MP4, MOV, M4V, MKV and AVI get H.264 video; WebM gets VP9, MPEG gets MPEG-2 and OGV gets Theora.
Picture quality: Always re-encoded once at a fixed quality; there is no quality setting. H.264 uses CRF 23, VP9 uses CRF 32.
Frame rate and size: Frame rate matches the source, capped at 60 fps when the speed changes. Width and height stay the same; an odd value is rounded up to the next even number of pixels.
Audio: Re-encoded at 128 kbps: AAC in MP4, MOV, M4V and MKV, MP3 in AVI, MP2 in MPEG, Opus in WebM, Vorbis in OGV. AAC, MP3 and MP2 are mixed down to stereo. If the file has several audio tracks, only one is kept. Videos without sound stay silent.
Maximum file size: 200 MB per video
Files per job: 1
Processing: On our servers with FFmpeg. A job can run for up to 15 minutes, so Motion interpolation on long HD clips at low speeds may not finish in time.
Watermark: None
Storage: Uploads and results are deleted automatically after 48 hours for guests and after 30 days for free accounts. Paid plans can keep files longer.

Frequently asked questions

Can I speed up only part of a video?

No. The chosen speed applies to the whole file. Trim the section you need with Cut Video first, then change its speed here.

Why does my slow-motion clip look jerky?

With Duplicate frames, a 30 fps clip at 0.25x shows every real frame four times, so movement jumps in steps. Switch to Frame blend or Motion interpolation, pick a less extreme speed, or start from footage recorded at a higher frame rate.

Why is the new file larger than the original?

Slowing a video increases its duration and can increase the file size. The file is also re-encoded: phones often record H.265 at a modest bitrate, and the H.264 output can need more space for the same picture. Compress Video can shrink the result afterwards.

Does changing the speed reduce quality?

The picture is re-encoded once at a fixed quality, which costs a little detail. Resolution stays the same, and so does the frame rate up to 60 fps.

Is my video sent to an AI service?

No. The file is uploaded to our server and processed there with FFmpeg; no third-party service receives it. It is deleted automatically after the storage period listed above.