You’re staring at a video of your dog doing a backflip, or maybe a lightning strike you caught by total accident, and it’s just too fast. You want that cinematic, dramatic crawl. But then you realize Apple doesn't exactly put a giant "Slow Motion" button right in the middle of the screen for existing clips. It's buried. Honestly, it's a bit of a UI mystery why something so popular is tucked away behind three different menus.
If you’re trying to figure out how to slow videos down on iPhone, you've probably noticed that the Photos app treats "Slo-mo" videos and "regular" videos totally differently. It’s frustrating. One lets you drag a slider; the other requires you to practically be a film editor.
We’re going to fix that. Whether you’re working with a clip you just shot or something you downloaded from Instagram, here is the ground truth on getting that speed under control without making the video look like a choppy PowerPoint presentation.
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The Photos app trick for Slo-mo clips
First off, let’s talk about the videos you actually shot using the "Slo-mo" setting on your camera. This is the easiest scenario. Your iPhone captures these at a high frame rate—usually 120 or 240 frames per second (fps). Because there is so much data there, the phone can stretch the footage out without it looking jittery.
Open the Photos app. Find your video. Tap Edit in the top right corner.
See that row of vertical white lines at the bottom? That’s your speed map. The lines that are spaced far apart represent the parts of the video playing at normal speed. The lines bunched tightly together are the slow-motion sections. You just grab those two taller vertical bars and slide them.
It's intuitive, but here’s the kicker: this only works for native Slo-mo files. If you try this on a standard 30fps or 60fps video, those speed lines won't even show up. You’ll just see the trim tool. It feels like a dead end, but it isn't.
How to slow videos down on iPhone using iMovie
If your video wasn't shot in Slo-mo mode, the Photos app is basically useless for speed changes. You need more horsepower. Most people forget they have iMovie sitting right there in their app library, completely free. It is the most reliable way to handle this without downloading some sketchy third-party app filled with ads.
- Launch iMovie and start a new Movie project.
- Select your clip from the library and tap Create Movie.
- Tap the clip on the timeline so it's highlighted in yellow.
- Look at the toolbar at the bottom. Tap the Speed icon (it looks like a little speedometer).
- Drag the slider toward the turtle.
You can go down to 1/8th speed. But a word of warning: if you slow down a standard 30fps video to 1/8th speed, it’s going to look terrible. Why? Because you’re asking the iPhone to turn 30 frames into 240. The phone has to "guess" what those missing frames look like or just repeat the same frame over and over. It gets stuttery.
If you want it to look "pro," try not to go below 1/2 speed (0.5x) for standard videos. If you shot it at 60fps, you can comfortably go to 1/2 speed and it’ll still look like buttery smooth cinema.
The "Save to Files" workaround for frame rate nerds
Sometimes iMovie feels like overkill. Or maybe you want to preserve the metadata perfectly. There is a weird quirk in iOS where you can sometimes "force" a speed change by using the Speed Up or Slow Down functions in the hidden playback menu, but that only changes how it looks while you watch it, not the file itself.
To actually change the file, you really have to use an editor. But here’s a tip: if you’re using an iPhone 15 Pro or 16 Pro and shooting in ProRes, the file sizes are massive. Slowing these down in iMovie might cause your phone to heat up. In those cases, I actually recommend using LumaFusion. It’s a paid app, but it handles high-bitrate slowdowns way better than Apple’s native tools. It uses better interpolation algorithms to "fake" those missing frames if you really need to go super slow.
Why your slowed-down video looks "ghostly"
Have you ever slowed a video down and noticed a weird blur? That’s shutter speed. When you record a normal video, the camera uses a shutter speed suited for 30 or 60 fps. When you stretch that out, the motion blur that looked natural at normal speed suddenly looks like a smeary mess.
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Professional videographers like Peter McKinnon often talk about the "180-degree rule." Basically, if you know you’re going to slow a video down later, you should shoot it at a high frame rate (like 60fps or 120fps) from the start. Your iPhone does a decent job of adjusting this automatically in Slo-mo mode, but if you’re using the "Video" mode, the phone favors a lower shutter speed to let in more light.
If you’re in a low-light environment, like a dark club or a sunset beach, and you try to slow that video down, it’s going to look noisy and blurry. There's no AI fix for that yet that actually looks good on a mobile device.
Third-party apps that don't suck
Look, iMovie is fine, but it’s clunky. If you do this a lot for TikTok or Reels, you probably want something faster.
- CapCut: Everyone uses it for a reason. The "Speed" tool has a "Curve" feature. This is huge. Instead of the whole video being slow, you can have it start fast, dip into slow motion for the impact, and then speed up again. It’s called a speed ramp.
- VN Video Editor: This is my personal favorite for clean edits. It’s free, has no watermarks (if you delete the end credit clip), and the speed ramping is even more precise than CapCut.
- Slow Fast Slow: An oldie but a goodie. It was designed specifically for this one task. It uses the iPhone’s native resources to manipulate frame rates without much compression loss.
The Instagram/TikTok shortcut
Kinda lazy? Me too. If you’re just posting to social media, don't bother with iMovie.
Upload the video to your Stories or the Reels editor. Tap the "1x" button on the side. You can instantly change it to 0.5x or 0.3x. The downside? You can’t save that video back to your camera roll without the Instagram UI gunk sometimes, and the quality takes a hit because of Instagram's compression. But for a quick "look at this" moment, it’s the fastest path.
Dealing with the audio pitch shift
When you slow down a video, the audio usually turns into a demonic, low-pitched growl. It’s creepy.
In iMovie, when you tap the speed slider, there’s a toggle for "Preserve Pitch." Flip that switch. It uses a digital stretch to keep the person's voice sounding like a human, just a very slow-talking human, rather than a giant. If you’re using CapCut, this is often the default, but always double-check. Nothing ruins a cool slow-mo shot of a kid laughing like it sounding like a horror movie trailer.
Common misconceptions about iPhone frame rates
A lot of people think that if they have a 4K video, they can slow it down more. That’s not how it works. Resolution (4K vs 1080p) is about detail; Frame Rate (fps) is about motion.
You can have a 4K video at 24fps (the cinematic standard) and if you slow it down, it will look like a flickering strobe light. You are better off shooting 1080p at 120fps if the goal is slow motion. Some newer iPhones can do 4K at 120fps, which is the "holy grail," but check your settings under Settings > Camera > Record Slo-mo to see what your specific hardware can actually handle.
Actionable steps to get the best result
If you want the highest quality "slowed down" video, stop using the regular Video mode.
Go to your camera settings right now. Set your Slo-mo to 1080p at 240 fps. It takes up more space, but the results are night and day. If the video is already recorded at a standard speed, bring it into VN Video Editor instead of iMovie. Use a "Curve" preset to add a bit of style to the transition.
Avoid slowing down any video shot in "Night Mode" or extremely dark settings. The sensor just can't keep up with the frame demands, and you'll end up with a grainy mess that no amount of editing can save. Stick to well-lit environments for anything you plan to manipulate in post-production.
Lastly, remember that once you export a slowed-down video from an app like iMovie, it becomes a "baked" file. You can't easily "un-slow" it later without losing a massive amount of quality, so always keep your original clip in your library just in case you change your mind.