Which video format should you use? A decision guide

The default: MP4 with H.264

If you take one thing from this guide: MP4 carrying H.264 video and AAC audio plays on effectively everything made in the last decade — every browser, phone, tablet, TV, console, and editing app. Hardware decoding for H.264 is built into essentially every chip, so playback is smooth and battery-friendly even on old or cheap devices. When someone asks what format to send, upload, or save a video in and there is no special context, "MP4" is the correct answer and the conversation can end there.

That is precisely why the most common conversions all point toward it — MKV → MP4, WebM → MP4, MOV → MP4. They exist to take video from a more specialized world into the universal one. (Strictly, the format is a container and H.264 is the codec inside it — the distinction is worth ten minutes via our containers vs codecs guide, but for choosing, "MP4" as shorthand serves fine.)

The four genuine exceptions

WebM — when you serve video on your own website

WebM is the web-native format: open, royalty-free, built around the VP8/VP9 codecs, and typically 20–40% smaller than H.264 MP4 at comparable quality. For pages you control — hero videos, background loops, demo clips — that saving is real bandwidth and faster loads. Its weakness is reach: Safari and iOS support is inconsistent and older TVs ignore it, so the robust pattern is offering WebM with an MP4 fallback, or just MP4 alone when you would rather not think about it.

MOV — when your world is Apple or a pro editing suite

MOV is Apple's QuickTime container: the native output of iPhones and the most frictionless input for Final Cut and much of the professional editing ecosystem, where it often carries high-fidelity intermediate codecs like ProRes. Inside that workflow, stay in MOV. Outside it, MOV mostly behaves like a less-compatible MP4 — the two are close cousins — which is why MOV → MP4 is one of the most common conversions there is: iPhone footage heading somewhere other than an Apple device.

MKV — when you are archiving, not sharing

MKV is the archivist's container: open, essentially unrestricted, happy to hold multiple audio languages, several subtitle tracks, chapters, and any codec in one file. Desktop players like VLC handle it perfectly; browsers, phones, and many TVs do not. So it makes an excellent shelf format and a poor sharing format — keep the MKV as the master and generate an MP4 copy whenever one is needed. (Converting MKV to MP4 often just re-packages the streams without re-encoding, so the copy can be fast and lossless.)

GIF — when the destination only takes images

Not really a video format, but it competes with one for short clips in chats, docs, and READMEs — a big enough topic that it has its own guide.

Destination table

What about H.265, AV1, and "the future"?

Newer codecs genuinely compress better — H.265 and AV1 reach similar quality to H.264 in roughly half the bits, and AV1 is royalty-free and heavily backed by streaming platforms and browser vendors. What they lack is a decade of hardware decoders in every pocket: older and cheaper devices decode them slowly, hot, or not at all. They are superb inside platforms that control playback (YouTube and Netflix serve them constantly) and still a gamble for files you hand to arbitrary people or devices. The safe expectation: AV1 gradually inherits the default crown over the coming years, and until your audience's devices are known to handle it, H.264-in-MP4 remains the format that never embarrasses you.