How to change video speed on a Mac
Whether you want to speed up a long clip into a snappy time-lapse or slow it down for a dramatic slow-mo, changing a video's speed shouldn't need a timeline editor, an account, or an upload to some website. Here's how to change the speed of a video on a Mac in seconds, 100% offline — anywhere from 0.1× to 8× — with the audio kept in sync and pitch-corrected and either by typing it in plain English or by using the Speed lane.
The fastest way: just ask
Crisp has a plain-English box ("Or just tell Crisp what to do…"). Drop your video in and say what you want:
- speed it up (defaults to 2×) or speed it up 4x
- slow it down (defaults to half speed) or 3x slower
- make it 2x faster, double the speed
- slow motion, half speed
Crisp reads the request, shows you the plan, switches to the Speed lane and sets the factor for you — you just press the button. And if you ask for a bigger edit in the same breath, "speed it up and upscale to 4K", the enhancement rides along instead of being dropped.
The manual way: the Speed lane
-
Open Crisp and drop in your video
Get the free Crisp app for Mac and drag your clip onto the window. Nothing is uploaded: the whole job runs on your Mac.
-
Ask for Speed
In Crisp, type “speed it up 2x” in the prompt bar at the top — plain English maps straight to the tool, and Crisp shows you what it is about to do before it runs. It's for video clips; if you've staged a photo, Crisp will nudge you to pick a video.
-
Choose a speed
Pick a preset — 2× faster, 0.5× (half speed) — or set any factor from 0.1× to 8×. Above 1 speeds up; below 1 slows down.
-
Press Change speed
Crisp rescales the video and pitch-corrects the audio on-device with hardware encoding, and saves the result beside your original: one-time. Staged several clips? It re-times each one in the same batch (batch is part of the one-time $129 Pro unlock; one file at a time is free).
The audio is done right
Naively speeding up a clip makes voices sound like chipmunks; slowing it down makes them drone. Crisp pitch-corrects the audio as it re-times it, so a 2× clip still sounds natural and a 0.5× one stays intelligible, and the sound stays perfectly in step with the picture. It handles big changes too, chaining the time-stretch in stages so even 8× or 0.1× comes out clean.
Speeding up vs slowing down — and smooth slow-mo
Speed is one lane that goes both ways. A factor above 1× speeds the clip up (great for condensing a long screen-recording or making a time-lapse); a factor below 1× slows it down (0.5× is half speed, 0.25× is quarter-speed slow motion). For really smooth slow motion, Crisp can also interpolate extra in-between frames so the slowed clip doesn't look choppy — see the dedicated slow-mo guide.
The range, and why the voices don't go squeaky
The lane accepts anything from 0.1× to 8×, with 0.25×, 0.5×, 2× and 4× as one-click presets. Speeding a clip up shortens it by the same factor — a 10-minute screen recording at 4× is 2.5 minutes.
The part worth explaining is the audio. Change the playback rate naively and the pitch goes with it: the chipmunk at 2×, the horror-film drone at 0.5×. Crisp pitch-corrects instead, so a sped-up voice still sounds like the person talking, just faster. The filter that does it only accepts a factor between 0.5 and 2 in a single pass, so anything beyond that is applied in stages whose product is the speed you asked for:
| Speed | Applied as | Stages |
|---|---|---|
| 0.1× (slowest) | 0.5 × 0.5 × 0.5 × 0.8 | 4 |
| 0.25× | 0.5 × 0.5 | 2 |
| 0.5× / 2× | one pass | 1 |
| 4× | 2 × 2 | 2 |
| 8× (fastest) | 2 × 2 × 2 | 3 |
Below 1× this lane slows the clip by holding each frame longer — no new frames are invented. That is the right answer for a screen recording or a talking head, and the wrong one for fast motion, where held frames read as judder. For that, the slow-mo lane generates the in-between frames instead.
Crisp vs iMovie vs QuickTime for changing speed
| Crisp | QuickTime | iMovie | Online tools | |
|---|---|---|---|---|
| Speed up AND slow down | Yes — 0.1×–8× | Playback only | Yes (presets) | Yes |
| Pitch-corrected audio | Yes | — | Often chipmunk | Varies |
| Plain-English ("slow it down") | Yes | No | No | No |
| Speed + enhance in one step | Yes | No | No | No |
| 100% offline, nothing uploaded | Yes | Yes | Yes | Uploads your clip |
| No watermark | With Pro ($129) | Yes | Yes | Often watermarked |
| Price | Free tier + one-time $129 · or 4 × $32.25 | Free | Free | Free + upsell |
QuickTime has a Playback Speed control but it only changes how the clip plays — there is no way to save a sped-up or slowed-down file (Apple's QuickTime Player guide, read 8 September 2026); iMovie can change speed, and shifts the audio pitch unless you tick its Preserve Pitch box. Crisp keeps it natural and does both directions in one lane.
Why offline matters for changing speed
- Your footage stays yours. The web "change video speed online" tools upload your clip first. Crisp re-times it entirely on your Mac — nothing leaves the device.
- No queue, no size cap. Cloud tools throttle by file size and make you wait; Crisp works on the whole file locally.
- The audio sounds right. Pitch-corrected sound, locked to the picture, at any factor.
- Batch a whole set. Stage several clips and Crisp re-times each one in a single batch.
Change your first clip's speed — offline
Free to try on your Mac. Speed up or slow down, pitch-corrected audio — no account, no subscription, nothing leaves your device.
Download Crisp for MacApple Silicon · macOS 26+ · Notarized
Speed changes, in detail
How do I speed up or slow down a video on a Mac for free?
Use Crisp: drop your clip in, select the clip and set its Speed (or type "speed it up" or "slow it down"), choose a factor, and press Change speed. It re-times the video and keeps the audio pitch-corrected, entirely on your Mac, with no account, no upload.
Does changing speed keep the audio in sync?
Yes — Crisp re-times the audio to match and pitch-corrects it, so it stays in sync and sounds natural instead of chipmunky or droning.
How fast or slow can I make it?
From 0.1× (ten times slower) up to 8× (eight times faster). 2× and 4× are common for speeding up; 0.5× and 0.25× for slow motion.
Is slow motion the same thing?
Slow motion is just a speed below 1×. The Speed lane does both directions; for extra-smooth slow-mo, Crisp can also interpolate in-between frames.
Can I change a photo's speed?
No — speed only applies to video, so the Speed lane is video-only. If you've staged a photo, Crisp will point you to a video clip.
Related guides
Slow-mo a video · Reverse a video · Trim a video
Background: how frame interpolation works.