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Convert MP4 to WebM Online Free

WebM is for your website. Make it lighter than the MP4.

People convert to WebM for one reason: a smaller video on a web page. Choose what the video is for, pick the codecs, and we hand you the files plus the exact HTML that lets each browser take the lightest one it can play.

wallpaperBackground loopmuted · autoplay · loops

play_circleProduct clipwith controls & sound

animationTransparent animationalpha channel · over page

source · hero-loop.mp4 · H.264 · 6.5 MB10 s · 1080p

check_boxAV1 · WebMnewest · smallestslow encode · ~4 min2.9 MB

check_boxVP9 · WebMwide supportmedium · ~1.5 min4.0 MB

check_box_outline_blankVP8 · WebMoldest WebMfast · ~40 s6.8 MB

lockH.264 · MP4fallback · alwayskept as-is6.5 MB

resolution

720p1080p1440p

sound

mutedOpus

paste into your pagebackground loop

Browsers read the sources top to bottom and play the first one they understand, so the lightest file goes first and the MP4 stays last as the safety net.

files3lightest2.9 MBsaving−56%

autorenewEncode 2 WebM files

Open MP4, MKV, MOV, AVI, WMV, FLV, RealMedia, DVD VOB, camcorder MTS or almost anything else, and save it as any of 32 formats. The converting happens in this tab. Your video is never uploaded.

video_fileChoose videosscienceMake a 6 s test clip

memoryThe enginenot loaded

whatFFmpeg compiled to WebAssembly

download≈ 31 MB, once per visit

readsloads with the engine

writes32 targets, checked on load

loads when you convert, or nowdownloadLoad now

~/convert

Your files, then one of 32 targets.

Each file is identified from its first bytes as soon as you add it. Once the engine is loaded it is read in full, so you see the real codecs, size and length before you convert.

filefirst bytessizeinside (read by engine)status

movieclose

upload_fileDrop videos hereor click to choose. Any container, any size your device can hold.

Save asreadyno sound trackafter engine loads

Common6 formats

.mp4.avi.mkv.mov.wmv.flv

Web3 formats

.webm.ogv.m4v

Professional5 formats

.mpg.mpeg.vob.mts.m2ts

Mobile2 formats

.3gp.3g2

Legacy4 formats

.rm.rmvb.asf.swf

Codec & camera12 formats

.av1.avchd.divx.f4v.hevc.m2v.mjpeg.mpeg-2.mxf.ts.wtv.xvid

Size

Keep1080p720p480p

Quality

HighBalancedSmall file

Sound

KeepMonoRemove

Frame rate

Keep30 fps24 fps

Length

Whole videoFirst 30 sFirst 10 s

Common · container · since 2001.mp4checked on load

MPEG-4 Part 14 on the ISO base media format. The safest choice when a file has to play anywhere.

file you getvideo.mp4

containermp4

videoH.264 (x264) (if in build)

soundAAC

best forWeb, phones, social, sharing

this browser plays itmaybe

command it runs

ffmpeg -i input.mp4 -map 0:v:0 -map 0:a:0? -vf "scale=trunc(iw/2)*2:trunc(ih/2)*2" -c:v libx264 -preset veryfast -crf 23 -pix_fmt yuv420p -c:a aac -b:a 128k -ac 2 -f mp4 -movflags +faststart video.mp4

no files yetboltConvert to .mp4

Results, read back by the enginefolder_zipDownload all as ZIP

from · downloadDownload

~/why-smaller-matters

On a phone, every megabyte is a second of blank box.

A hero video only starts once enough of it has downloaded. Pick a connection and watch the same 10-second loop arrive in each format. The bars fill in real proportion.

signal_cellular_alt_1_barSlow 4Gsignal_cellular_altGood 4GwifiHome Wi-FireplayReplay

MP4 · H.2646.5 MB1.2 sstarts playing

WebM · VP94.0 MB0.7 sstarts playing

WebM · AV12.9 MB0.5 sstarts playing

white tick = enough downloaded to start (first 2 seconds of video) · Good 4G ≈ 9 Mbit/s · 10 s at 1080p

~/see-through-video

WebM can carry a transparent background. MP4 can't.

VP8 and VP9 in WebM support an alpha channel, so an animated mascot or product spin can float over any page colour. H.264 MP4 always has a solid box. If your source was made with transparency (for example exported as ProRes 4444), keep it by converting to WebM.

page background

MP4 · H.264solid box

The transparent areas are filled with a colour when encoded, here white, so a box shows on anything that isn’t white.

WebM · VP9 with alphatransparent

Only the character is drawn. It sits on whatever the page behind it is, including photos and gradients.

~/who-plays-what

Why the MP4 stays in the list.

Chrome, Firefox and Edge play every WebM codec. Apple devices are the catch: VP9 needs a recent Safari, and AV1 only decodes on newer Apple chips. The H.264 fallback guarantees that nobody sees a broken player.

browserVP8WebMVP9WebMAV1WebMH.264MP4publicChromecheck_circleplayscheck_circleplayscheck_circleplayscheck_circleplayspublicEdgecheck_circleplayscheck_circleplayscheck_circleplayscheck_circleplayspublicFirefoxcheck_circleplayscheck_circleplayscheck_circleplayscheck_circleplayslaptop_macSafari (Mac)errorrecent versionserrorrecent versionserrornewer chips onlycheck_circleplaysphone_iphoneSafari (iPhone)errorrecent versionserrorrecent versionserrornewer chips onlycheck_circleplaysphone_androidAndroid browserscheck_circleplayscheck_circleplayscheck_circleplayscheck_circleplays

~/other-routes

Not for a web page? WebM may be the wrong choice.

For sharing, editing and phones, MP4 is still the format everything accepts.

compressVideo compressorNeed a smaller MP4 for sharing rather than a website? Shrink it and keep the format everyone accepts.clip.mp4 · 82 MBarrow_forward12 MB gif_boxVideo to GIFOld email clients and some chat apps still want GIF. WebM is far smaller if the page supports it.loop.mp4arrow_forwardloop.gif movie_editVideo editorTrim a seamless loop point before converting, so the background doesn’t jump.0:00-0:10arrow_forwardhero-loop.mp4 swap_horizVideo converterEvery other video format, including WebM back to MP4.clip.webmarrow_forwardclip.mp4

Sources

[1]WebM containerThe official WebM project: codecs, container and licensing.webmproject.org ↗[2]The video elementHow browsers choose between multiple <source> elements.MDN Web Docs ↗[3]AV1 codecThe royalty-free codec from the Alliance for Open Media.Alliance for Open Media ↗

Frequently Asked Questions

Is converting MP4 to WEBM free?

Yes, MP4 to WEBM conversion is completely free with no signup, no watermark, and no usage limit. Convert as many files as you need.

Are my files uploaded to a server?

No. The MP4 to WEBM converter runs in your browser when your file is supported there, so the file stays on your device for that workflow, reducing server exposure for that workflow. Look at the processing mode before putting anything confidential through it.

How long does MP4 to WEBM conversion take?

Most MP4 to WEBM conversions finish in under a minute. A large file takes longer in proportion, though the work happens on your machine, so nothing waits on a sign-up.

Will the conversion reduce file quality?

Depends which formats. Lossless in, lossless out, and the file you get back is identical. Convert to something compressed and you trade a little quality for a smaller file, which is usually the trade you wanted.

Does this work on mobile devices?

Yes. The MP4 to WEBM converter works on phones, tablets, and desktops in any modern browser including Chrome, Safari, Firefox, and Edge.