tinyvid.dev

Convert MP4 to WebM

Convert MP4 to WebM online for a smaller, web-ready video. TinyVid re-encodes your H.264 MP4 to VP9 with Opus audio and hands you the embed code. Free up to 200 MB, no sign-up, no watermark.

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MP4 · MOV · AVI · MKV · WebM · GIF|Free up to 200 MB
01About the conversion

Why convert MP4 to WebM?

MP4 with H.264 is the universal video format — it plays everywhere, which is why phones, cameras and editors export it by default. But H.264 is a codec from 2003, and for a modern website you can often get the same picture in fewer bytes.

WebM is an open, royalty-free format built for the web. TinyVid writes it with VP9 video (not the older VP8) and Opus audio. At the same visual quality VP9 usually needs noticeably fewer bits than H.264, so pages load faster and the video starts sooner on slow connections. How much you save depends on the source — an MP4 straight from a phone or camera has plenty to give, while one already squeezed for the web has less.

MP4 vs WebM in practice: MP4 is the format to send someone, upload to social networks or open in an editing app — those re-encode or expect MP4 anyway. WebM is the format to serve from your own site: hero and background loops, product demos and tutorial clips. VP9 WebM plays in Chrome, Firefox, Edge, Android and Safari on Mac, and on iPhones from iOS 17.4.

Converting MP4 to WebM re-encodes the video to VP9 and the audio to Opus — WebM can't carry the AAC track most MP4 files use. The Standard player preset keeps the sound and caps the short side of the frame at 1080 pixels, so a 4K phone clip comes out web-sized; Max compression goes down to 720p at 24 fps with no audio. If the WebM would come out heavier than your MP4 — it happens with sources that are already well compressed — TinyVid re-encodes an H.264 clip of up to five minutes at a tighter setting, and the result shows the real size change either way.

Not sure WebM is the right call? If your visitors include older iPhones, keep the default Auto instead: TinyVid makes a compact AV1 file plus an H.264 MP4 fallback and lists both in the embed code, so every browser picks one it can play.

02Step by step

How to convert MP4 to WebM

  1. Drop your .mp4 file above or browse — files up to 200 MB are free, no sign-up.
  2. The output is already set to VP9 WebM. Keep Standard player for a video with sound, or pick Max compression for the smallest silent file.
  3. Optional: open Advanced settings to adjust Quality and resolution, trim the clip or set a target file size.
  4. Press Convert — TinyVid re-encodes the MP4 to VP9 WebM on its servers and shows how the size changed.
  5. Download the .webm or copy the embed code and paste it into your page.
03FAQ
01How do I convert MP4 to WebM for free?
Upload the .mp4 above and press Convert — files up to 200 MB convert to WebM for free with no account and no watermark; up to 4 GB is a one-time payment by size. Need the other direction? There's a WebM to MP4 page under Related conversions.
02Is WebM smaller than MP4?
Usually, yes. VP9 compresses tighter than the H.264 inside most MP4 files, so the WebM is often noticeably smaller at the same visual quality. An MP4 that is already heavily compressed — or one that holds HEVC rather than H.264 — has less to give, and the result screen shows the real size change either way.
03MP4 or WebM — which is better for a website?
For video you serve yourself on modern browsers, WebM is usually the lighter file. For the widest reach, list the WebM first and an MP4 second in the <video> tag — each browser plays the first one it supports. If you'd rather not manage two files, the Auto setting makes the pair for you (see the next question).
04Will a WebM play in every browser and on iPhone?
VP9 WebM plays in Chrome, Firefox, Edge, Android and Safari on Mac. iPhones play it from iOS 17.4; if your audience includes older ones, choose Auto instead — TinyVid then makes an AV1 file with an H.264 MP4 fallback in the embed code.
05Does converting MP4 to WebM reduce quality?
Any re-encode is lossy, but VP9 holds detail well, so on the Standard player preset the difference is usually invisible. Push the Quality slider up in Advanced settings to preserve more, or down for a smaller file.
06Does the WebM keep the audio?
Yes, with the Standard player preset: the sound is re-encoded to Opus, the audio codec WebM uses. Hero background and Max compression make a silent file, and Mute audio in Advanced settings drops the sound on any preset.
07Can I convert MP4 to WebM at a specific file size?
Yes. In Advanced settings, pick a Target size — 8, 10, 25, 50 or 100 MB, or your own — and TinyVid sizes the WebM to fit just under it. The Quality slider is off in that mode, and very long clips may need a bigger target; TinyVid tells you the smallest one that works before you upload.
08How do I embed the WebM on my website?
Copy the embed code from the result: a <video> tag with the WebM as its only source and the real width and height of the output, so the page doesn't jump while it loads. To cover older iPhones, add an MP4 as a second <source> after the WebM; converting the same file with Auto gives you a compact one.
09Can a WebM have a transparent background?
Only if the source has one. VP9 WebM can carry an alpha channel, but a regular H.264 MP4 has none, so a WebM converted from it is opaque. For transparent video, start from a MOV with alpha, such as ProRes 4444 — see MOV → WebM under Related conversions below.
10Do I need an account to convert MP4 to WebM?
No sign-up for free or one-time paid conversions — everything runs online. Your file is converted on our servers, and both the MP4 and the WebM are deleted automatically within 24 hours.