Video Speed Tool

Slow-mo, fast-forward, timelapse. Adjust freely between 0.25x and 4x. Outputs MP4.

Local processing — no upload

⏩

Drop a video, or tap to select

MP4 / MOV / WebM / MKV

🎬

—

0.25x

Super slow

0.5x

Slow

Normal

1.5x

Fast

Double

Timelapse

Custom

Speed multiplier (0.25–4.0, 1.0 = normal) 1.00x

Define segments with start/end/rate (no overlaps). Untouched parts play at normal speed.

Audio handling

Resolution

Estimated duration: — → —

Processing… 0%

Download converted video

What to do next

Command Reference

Change Video Speed with FFmpeg (setpts / atempo) →

Related Tools

Video Reverse Tool Video Trim Tool

Popular uses

Create timelapse clipsSlow-motion playbackAdjust tutorial length

Next tools

Video Trim Tool Audio Extractor Video Reverse Tool

What this tool does

Speed range 0.25× to 4× with one-tap presets
Per-segment variable speed for selective fast-motion / slow-motion
Audio modes: time-stretched (atempo), muted, or original
Resolution preserved or downscaled to taper file size
All processing runs locally

How to use

1
Drop your video
MP4 / MOV / WebM, etc.
2
Pick a speed
Use a preset (0.5× / 1.5× / 2× / 4×) or enter a custom value. Switch to variable mode for segment-level control.
3
Choose audio mode
In sync (atempo), muted, or original (will desync at non-1× speeds).
4
Run the conversion
Preview and download once processing finishes.

What each setting means

Speed factor

0.25–4×. Below 1× = slow motion; above 1× = fast motion.

Audio mode

In sync = stretches audio with atempo (preserves pitch). Muted = removes audio.

Resolution

Output resolution. Keep original or downscale to reduce file size.

Variable segments

Per-segment start / end / speed. Useful when only part of a clip should be slowed.

Recommended settings

Skim long footage at 2×

2× · audio in sync · keep resolution

atempo preserves pitch, so dialog stays understandable.

Sports slow motion

0.5× or 0.25× · audio muted · keep resolution

Slow motion is smoother on high-FPS source footage.

Time-lapse fast forward

4× · audio muted · downscale to 720p

High speeds make audio unnatural — mute is cleaner.

Common pitfalls

Symptom: Audio sounds noisy at high speeds

Cause: atempo only handles 0.5–2× per pass.

Fix: The tool auto-chains atempo, but at 4×+ we recommend muting audio.

Symptom: Slow-motion stutters

Cause: Source FPS is too low (≤ 30 fps).

Fix: Stay at 0.5×, or capture at 60 fps to start.

Symptom: Variable mode leaves gaps

Cause: Segment ranges do not chain end-to-start.

Fix: Make each segment’s end equal to the next segment’s start.

Equivalent FFmpeg commands

Reference commands you can run on the desktop FFmpeg CLI.

2× speed (audio pitch preserved)

ffmpeg -i input.mp4 -filter_complex "[0:v]setpts=PTS/2[v];[0:a]atempo=2[a]" -map "[v]" -map "[a]" out.mp4

0.5× slow motion

ffmpeg -i input.mp4 -filter_complex "[0:v]setpts=PTS*2[v];[0:a]atempo=0.5[a]" -map "[v]" -map "[a]" out.mp4

4× speed, no audio

ffmpeg -i input.mp4 -filter:v "setpts=PTS/4" -an out.mp4

Beyond atempo’s natural range — muting is cleanest.

Browser support & limits

Recommended max file size: 500 MB
Speed range: 0.25–4×
Up to 8 variable-speed segments

Privacy

This tool runs ffmpeg.wasm directly in your browser. Files never leave your device — everything runs locally. Read the privacy policy →

Frequently asked questions

Can I keep the original audio pitch?

Yes — “Audio in sync” uses FFmpeg’s atempo filter, which time-stretches audio while preserving pitch. This is the default.

Variable speed vs. uniform speed?

Uniform applies one factor to the whole video; variable lets you say “0–10s normal, 10–15s 0.25×, 15s+ 2×.”

Can I go slower than 0.25×?

The tool clamps at 0.25×. For slower motion, run a second pass (0.25× → 0.25×) or use minterpolate on desktop FFmpeg.

Faster than 4×?

Beyond 4× is essentially time-lapse — frame-skip techniques work better than speed-up filters.

Why does audio drift?

Variable framerate (VFR) source is the usual cause. Convert to CFR with the Format Converter first.

Can I reverse playback here?

No — use the dedicated Reverse Video tool.