Video Converter

Choosing a target format

MP4 with H.264 plays literally everywhere — browsers, phones, TVs, PowerPoint, social platforms. If you are not sure, pick it. WebM with VP9 gets you a noticeably smaller file for web delivery, at the cost of a slower encode and older Safari versions refusing to play it. H.265 (HEVC) looks best per byte but is by far the slowest option here and has patchy browser playback. MOV is worth it only when something Apple-specific is on the other end of the file.

What CRF actually does

CRF — Constant Rate Factor — is the quality dial. Lower numbers mean better quality and larger files; the scale runs 0–51. 18 is visually near-lossless, 23 is the default and the right answer for most footage, 28 is a sensible ceiling when you need something small enough to email. Raising CRF compresses better than simply lowering the resolution, and it is usually the first dial to turn when a file is too big.

Two things worth knowing before a long job: re-encoding is the slow path — WebAssembly has no hardware encoder and no GPU access, so expect roughly real-time or slower on a laptop, and considerably slower for VP9 and H.265. If you only need a different container, or you are only cutting the ends off, use the trimmer in stream-copy mode instead; it finishes in a second or two and loses no quality at all.

Why convert locally?

Uploading a 2 GB video to a conversion service means a long wait before any work starts, a copy of your file sitting on a stranger's disk, and — on most free services — a length cap and a watermark. Your browser already has everything needed to do the job: the engine reads the file straight from disk, converts it in a worker thread, and hands it back as a download. Nothing is transferred, so there is no size limit and no privacy question to answer.

FAQ