Video FPS Converter & Smoothener

Convert 24 FPS and 30 FPS videos to smoother 60 FPS or 90 FPS with on-device frame interpolation. Free video processing with privacy in mind: nothing is uploaded.

Beta: this tool works for common files but is still being improved; see Limitations below.

About FPS Converter

Raises a video's frame rate to 30, 60 or 90 FPS by generating in-between frames from the motion between neighbouring frames, so 24 or 30 FPS footage looks smoother on high-refresh screens. It can also export a half-speed or quarter-speed slow-motion version, and it reports exactly how many frames were generated and how many were repeated.

How to use FPS Converter

  1. Add a video (MP4, MOV, WebM or MKV). The detected frame rate, resolution, duration and size appear.
  2. Choose the output rate: 30, 60 or 90 FPS.
  3. Choose a mode: Fast, Balanced (recommended), Quality, or Basic, which only repeats frames for apps that just need a higher-FPS file.
  4. Optionally lower the output resolution, choose Smaller file, Balanced or Higher quality, and set slow motion to 0.5× or 0.25×.
  5. Press Smooth. For videos over 10 minutes, a short speed test first estimates time, file size and disk space, and you choose where the output is saved.
  6. When it finishes, the output is re-opened and checked, then shown next to the original. Download it as an H.264 MP4.

When it helps

Smoother playback of game or screen captures

A 30 FPS gameplay clip converted to 60 FPS looks closer to what you saw while playing, especially on camera pans. Fast mode is usually good enough for this kind of content.

Slow motion from ordinary footage

Setting 0.5× or 0.25× spreads the source frames out and fills the gaps with generated frames, so slow motion doesn't stutter. The sound is dropped in this mode, because slowed audio would no longer match.

Long recordings such as lectures or full matches

Above 10 minutes the tool switches to long-video mode, processing roughly a minute at a time and saving each finished segment to disk. If the tab reloads or the laptop sleeps, choose the same file again and the job resumes from the last finished segment.

Tips

Limitations

What happens to your files

Decoding, motion estimation on the graphics processor and encoding all run in your browser; the video is never uploaded and no AI model is downloaded, because the interpolation is a motion-compensated algorithm rather than a neural network. For long videos, finished segments are written to the browser's private file storage (OPFS) and job progress to IndexedDB so the job can resume; with Chrome or Edge the final file streams to the location you pick. Those temporary segments belong to this site's storage and are removed when the job is cleaned up or when you clear site data.

Related guides

How to Use the Video FPS Converter

Add a video (MP4, MOV, WebM or MKV) by dropping it on the page or tapping Browse. The tool reads the frame timestamps and shows the detected frame rate, along with the resolution, length and size. Pick 30, 60 or 90 FPS, choose Fast, Balanced or Quality, and optionally a lower resolution or a smaller file. Press Smooth and watch the progress, elapsed time and time left; Cancel stops at once. When it finishes, the new file is opened again and checked (real frame count, duration, frame rate, size and sound), then shown next to the original so you can compare before downloading it as name_60fps.mp4. For a long video, a few-second speed test first estimates the processing time, output size and disk space; you then choose where to save the file, and can pause, stop and later resume the job.

How Motion Interpolation Creates New Frames

Between every two original frames, the converter estimates motion with a coarse-to-fine block-matching optical flow on your graphics processor: the picture is analysed at several scales, every point searches for where it moved, and outliers are filtered out. Balanced and Quality modes measure motion in both directions and check that the two agree, which reveals areas that are being covered or uncovered. Each new frame is then drawn by moving the pixels of both neighbouring frames part of the way along their motion and blending them by confidence, taking hidden areas from the frame where they are visible. Output frame k is placed exactly at k divided by the new frame rate, so the duration is unchanged and the original sound, copied without re-encoding when possible, stays in sync.

Limitations and Compatibility

Interpolation can only follow motion that is visible in both frames. Very fast or chaotic movement, motion blur, flashing lights, transparent objects and repeating patterns can produce warping, so where confidence is low the tool repeats the nearest original frame instead of guessing, and scene cuts are never blended. It cannot add detail that was never filmed. Clips up to 10 minutes are processed in memory. Longer videos, up to 4 hours on computers and 3 hours on phones, use long-video mode in browsers with file storage: about one minute at a time is processed and saved to disk, the finished segments are joined without re-encoding and the original sound is copied once, unchanged. Processing time grows with length and depends on the device's graphics hardware, the tab must stay open (background tabs can be slowed down), and enough free disk space for the output is needed; an interrupted job can be resumed from its last finished segment. Quality mode needs more memory and is several times slower than Fast. It works in recent Chrome, Edge, Firefox and Safari with WebCodecs; motion interpolation also needs WebGL2, and where that is missing only Basic conversion, which repeats frames and adds no new motion, is offered. The output is H.264 MP4.

Private, Free and Honest About What It Does

The whole process runs inside your browser: the video is decoded, analysed, re-encoded and saved on your device and is never uploaded. There is no sign-up and no watermark. The result screen states how many frames were motion-interpolated, how many are originals and how many were repeated at scene cuts or fast motion, so you know exactly what you are getting. For slow motion, a separate export plays the clip at half or quarter speed with interpolated frames; its sound is removed because slowed-down audio would no longer match.

Frequently asked questions

What does converting a video from 24 FPS to 60 FPS do?
FPS is the number of pictures shown per second. A 24 FPS video has 24 frames each second; at 60 FPS the player shows 60. The converter lays 60 frames per second along the same timeline: an output frame that falls exactly on an original frame reuses it, and every other one is generated from the two original frames around it, so motion looks more fluid. The length of the video and its sound stay exactly the same.
How does the frame interpolation work?
For each pair of neighbouring frames, the tool estimates where every part of the picture moves (optical flow, computed on your GPU at several scales and in both directions), then draws new frames part-way along that motion. Areas that appear or disappear between frames are taken from the frame where they are visible. It is motion-compensated interpolation, not an AI model, and not frame duplication or cross-fading (that only happens in the clearly labelled Basic mode).
Which mode should I choose, and how long does it take?
Balanced suits most videos. Fast uses a lower-resolution motion map and finishes sooner; Quality estimates motion at near full resolution with two passes and is slower and uses more memory. Speed depends on your graphics hardware, the resolution and the output frame rate: the progress bar shows frames per second, elapsed time and the time left, and you can cancel at any moment.
Is my video uploaded?
No. Decoding, motion estimation, frame generation and encoding all run in your browser on this device, using WebCodecs and WebGL2. The video file is never sent to a server.
What happens at scene cuts and very fast motion?
Scene cuts are detected by comparing the brightness histograms of neighbouring frames, and the new frames there repeat the nearest original frame, so two shots are never blended into a ghosted picture. Where motion is too fast or chaotic to follow reliably, the tool also repeats the nearest frame instead of inventing motion. The result screen tells you how many frames were interpolated and how many were repeated.
Which browsers and devices are supported?
Recent Chrome, Edge, Firefox and Safari on computers, and recent Android and iPhone browsers. Motion interpolation needs WebGL2; where it isn't available only Basic conversion (repeated frames) is offered. Videos up to 4 hours are accepted on computers and 3 hours on phones in browsers that can save files to disk (browser storage); otherwise the limit is 10 minutes on computers and 3 on phones. The output is an H.264 MP4 that plays almost everywhere.
Can it convert a full-length movie?
Yes. Videos over 10 minutes switch to long-video mode: the movie is processed in segments of about a minute that are saved to disk as they finish, so memory use stays flat however long it is, and the output is written straight to a file you choose (Chrome and Edge) or kept in browser storage for download. A short speed test first estimates the time, file size and disk space needed. Time depends on your graphics hardware, the resolution and the mode: the speed test gives an estimate for your device before you start, and Balanced and Quality take several times longer than Fast. Keep the tab open and in front. You can pause, and if the tab crashes, reloads or the computer sleeps, open the page again, choose the same file and resume from the last finished segment.

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