Frame Rate Converter

About Frame Rate Converter

This online frame rate converter lets you change the FPS (frames per second) of your videos, including broadcast rates like 23.976, 29.97 and 59.94 FPS or any custom value from 1 to 120 FPS. Tune output quality with CRF, pick the codec/container (MP4/H.264, WebM/VP9, MOV, AVI), and export a web-optimized +faststart master. All processing runs locally in your browser via FFmpeg.wasm, so your video is never uploaded.

What video formats are supported?

Input: MP4, WebM, MOV, AVI and other common formats. Output: You can keep the same format as input or convert to MP4, WebM, MOV, or AVI.

How do I convert video frame rate?

Upload your video, select target FPS using presets (24, 25, 30, 50, 60, 120) or custom slider (1-120), choose interpolation method and quality, then click 'Convert Frame Rate'. You can preview and compare the result before downloading.

What is the file size limit?

The maximum file size is 100MB. This ensures smooth processing in your browser. For larger videos, consider using desktop video editing software.

What are the common frame rates?

24 FPS: Cinema/film standard. 25 FPS: PAL TV standard (Europe). 29.97/30 FPS: NTSC TV/web video standard. 50 FPS: PAL high frame rate. 59.94/60 FPS: Smooth motion, gaming. 120 FPS: Very smooth, slow-motion source.

What is the difference between interpolation methods?

Duplicate Frames: Fastest, simply repeats/drops frames. Good for small FPS changes. Blend Frames: Balanced speed and quality, creates intermediate frames by blending. Motion Interpolation: Best quality, analyzes motion to create smooth intermediate frames. Slowest but best for large FPS increases.

What does Speed Mode do?

Keep Duration: Standard conversion, video plays at normal speed with new frame rate. Change Speed: Creates slow-motion (higher FPS) or fast-motion (lower FPS) effects. For example, converting 30fps to 60fps with Change Speed creates a 2x slow-motion effect.

How does the quality setting work?

The quality slider controls the CRF (Constant Rate Factor) for video encoding. Best quality produces larger files with minimal compression. Smallest produces smaller files but with more compression artifacts. Balanced is recommended for most uses.

What is the difference between 29.97 and 30 FPS (drop-frame timecode)?

29.97 and 59.94 FPS exist because NTSC color TV slowed the nominal 30/60 rate by a factor of 1000/1001 for backward compatibility, and 23.976 is film transferred to NTSC the same way. The fractional rate means real-time clock and frame count drift, so broadcast uses drop-frame timecode (29.97 DF) — it skips counting two timecode labels each minute (except every tenth minute) to stay aligned with the wall clock. It is only a labeling trick: no actual frames are dropped. Use the 23.976, 29.97 and 59.94 presets when you need to match an NTSC/broadcast delivery spec exactly rather than the rounded 24/30/60.

Will conversion add judder or 3:2 pulldown, and how do I go from NTSC 29.97 to PAL 25 or film 24?

Converting between rates that are not simple multiples (for example 23.976 to 29.97, the classic 3:2 pulldown case, or 29.97 NTSC to 25 PAL) will introduce some judder if you use Duplicate Frames, because whole frames are repeated or dropped on an uneven cadence. To minimize judder, choose Blend Frames (cross-fades neighboring frames) or Motion Interpolation (synthesizes new in-between frames from motion vectors). For NTSC-to-PAL or film conversion, keep Speed Mode on 'Keep Original Duration' and pick the 25 or 24 preset; the tool re-times frames while preserving runtime. Use Change Speed only when you intentionally want a slow-mo or fast-mo effect.

What is +faststart (Web Optimized) and why does web delivery need it?

Enable Web Optimized (faststart) for MP4/MOV output and the encoder relocates the moov atom (the index of where each frame lives) to the front of the file. Without it the index sits at the end, so a browser or CDN streaming the file progressively over HTTP cannot start playback until the entire file has downloaded. With faststart on, playback begins almost immediately — essential for any clip you will host, stream, or embed. It is on by default and only applies to MP4/MOV; WebM and AVI ignore it.

Does Change Speed stretch the audio, and what about CFR vs the source's VFR?

Yes. In Change Speed mode the audio is time-stretched with the atempo filter to match the new playback speed (pitch is preserved), so a 2x slow-motion clip keeps its audio in sync; clips with no audio track are handled gracefully. Note the output is always constant frame rate (CFR): if your source was variable frame rate (VFR), common with screen recordings and phone footage, the conversion re-times it to a steady cadence, which is what most editors and players expect for predictable playback and sync.

Will video quality be affected?

The video is re-encoded with your chosen quality settings. Frame rate conversion quality depends on the interpolation method chosen. Motion interpolation provides the best quality for increasing FPS.

Is my video file safe?

Absolutely! All video processing happens directly in your browser using FFmpeg.wasm (WebAssembly). Your video file is never uploaded to any server. Everything stays private on your device.

How long does processing take?

Processing time depends on video length, FPS change magnitude, interpolation method, quality setting, and device performance. Duplicate frames is fastest. Motion interpolation is slowest but highest quality.