Make a slow motion video online
This slow motion video maker slows a whole clip, or just the moment that matters, to anywhere between 0.75× and 0.1× of normal speed. Ease into the effect with a speed ramp, choose whether the missing in-between frames are blended or repeated, decide what happens to the sound, and download an MP4. Everything runs in your browser — the video is never uploaded.
Use it for the classic sports replay — a goal, a jump, a golf swing — for a dramatic beat in a wedding or travel film, for a splash, a hair flip or a product reveal in a social clip, or simply to see what happened in a fast moment. Segment mode keeps the rest of the clip at normal speed, so a 10-second video can slow down for its best second and then carry on.
The tool is also honest about what slow motion needs. It shows the source frame rate and how many real frames per second remain after slowing, because no software can invent detail that the camera never captured: footage shot at 120 or 240 fps slows down beautifully, while 30 fps footage at 0.25× has only 7.5 genuine images per second.
How to use the Slow Motion Video
- Drop a video onto the box or click to choose one. Its duration, resolution and frame rate are listed, and the original plays in the Before player.
- Choose a Slow-motion speed preset or type a value from 0.1 to 0.75.
- To slow only one moment, set Apply to to “One segment”, then scrub the Before player and press Set beside Slow from and Slow until. Adjust the Speed ramp for a gradual change.
- Pick In-between frames (Blend for smoother motion, Repeat for crisp frames), the Audio mode and, if you like, a different frame rate or size.
- Read the summary — new length and effective frame rate — then press Make slow motion and download the MP4.
Slow Motion Video features
0.1× to 0.75×
Six presets (0.75, 0.5, 0.33, 0.25, 0.2 and 0.1×) plus a custom value in 0.01 steps.
Segment slow motion with ramps
Slow just one section; smoothstep ramps ease the speed down and back up instead of switching abruptly.
Frame blending or repetition
Blend cross-fades the two nearest real frames for fluid movement; Repeat holds each real frame for a sharp, stepped look.
Effective frame-rate meter
See the source fps, the real frames per second left in the slow part and whether your footage gives true slow motion.
Three audio modes
Stretch the sound at its normal pitch (WSOLA), let it slow down and deepen, or mute it.
No upload
Decoding, frame blending and encoding all happen on your device with WebCodecs and the open-source Mediabunny library (MPL-2.0).
Why real slow motion needs high-frame-rate footage
A video is a series of still images. Slowing it down spreads those images over more time, so the number of real images per second drops: effective fps = source fps × speed. Players still need 24–60 frames each second, so the gaps are filled either by repeating frames (which looks stepped) or by blending neighbours (which looks smoother but can show ghosting on fast motion). Neither creates new detail.
That is why phones offer a 120 or 240 fps “slo-mo” mode. Footage like that can be slowed to 0.25× and still give 30–60 genuine frames every second. The table shows what to expect when the result plays at 30 fps.
| Filmed at | 0.5× | 0.25× | 0.1× |
|---|---|---|---|
| 24 fps | 12 real fps | 6 real fps | 2.4 real fps |
| 30 fps | 15 real fps | 7.5 real fps | 3 real fps |
| 60 fps | 30 real fps — smooth | 15 real fps | 6 real fps |
| 120 fps | 60 real fps — smooth | 30 real fps — smooth | 12 real fps |
| 240 fps | 120 real fps — smooth | 60 real fps — smooth | 24 real fps |
Tips for great slow motion
- Film in bright light: high frame rates use short exposures, and dim scenes become noisy.
- Keep the slow part short — one or two seconds of a 0.25× moment is usually more striking than a whole clip at half speed.
- Use a ramp of 0.2–0.5 s for a cinematic speed ramp; set it to 0 for an instant switch.
- Choose Blend for flowing movement such as water or dance, and Repeat for fast sport where ghosting would be distracting.
- If the clip is shaky, steady it first with Stabilize Video; for a uniform speed change up to 4× use the Video Speed Changer, and to cut the clip down first use Trim Video.
Slow Motion Video FAQ
How do I make a slow motion video from a normal video?
Open the clip, pick a speed such as 0.5× or 0.25×, choose Whole clip or One segment, and press Make slow motion. The result downloads as an MP4. Blend mode gives the smoothest look from ordinary 30 fps footage.
Can I slow down only part of a video?
Yes. Set Apply to “One segment”, choose where the slow part starts and ends, and add a speed ramp so the clip eases into and out of slow motion. Everything outside the segment stays at normal speed.
Why does my slow motion look choppy?
Your footage has too few real frames for that speed. A 30 fps clip at 0.25× has 7.5 real frames per second. Use Blend, choose a gentler speed, or film at 120–240 fps for genuinely smooth slow motion.
What does frame blending do?
It creates each in-between frame by mixing the two nearest real frames in proportion to time. Motion looks more fluid than repeating frames, but very fast objects can show a faint double image.
What happens to the sound?
By default it is time-stretched so voices keep their normal pitch, although extreme slow-downs sound echoey. “Slow and deep” lowers the pitch like a slowed tape, and Mute removes the audio.
Is my video uploaded?
No. The file is processed in your browser on your own device. It works offline once the page and the small video library have loaded.