WebM to MP4 Converter

Drag & Drop or Click to Select a WebM Video

WebM in, MP4 out

Tip: paste a video file from clipboard (Ctrl/⌘+V).

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Settings are written to the URL as you change them. Nothing differs from the defaults yet.

Convert a WebM file to an MP4 that plays on an iPhone, imports into an editor, and passes an upload form. The picture is re-encoded to H.264 and the sound to AAC.

Why WebM needs re-encoding

WebM is the web’s open format: VP9, VP8, or AV1 video with Opus or Vorbis audio. Every current browser plays it, but QuickTime, iOS, and most video editors do not, and changing the container alone does not fix that. MP4 can hold VP9 and Opus, yet those players still refuse the file.

H.264 and AAC in an MP4 is the combination nearly every device and program opens.

Screen recordings

Browser screen recorders and many recording extensions save WebM. Their content, text and flat interface colors, compresses well in H.264, so the MP4 keeps sharp edges at a similar file size. The frame size and frame rate are unchanged.

Timing

A WebM from MediaRecorder often has no duration stored in its header, which is why some players show it as endless or refuse to seek. The converter measures the real duration from the stream, and the MP4 it writes has a correct duration and seeks normally.

Frequently Asked Questions

Why does WebM to MP4 re-encode?

WebM holds VP9, VP8, or AV1 video and Opus or Vorbis audio. An MP4 can technically hold those, but QuickTime, iPhones, and most editors refuse them, so the video is re-encoded to H.264 and the audio to AAC to give a file that opens everywhere.

How long does it take?

Every frame is decoded and encoded again at the source size, so it takes much longer than a container change. Most Windows and Mac machines encode H.264 in hardware, which keeps a screen recording of a few minutes to a short wait.

Does the MP4 lose quality?

A little. Re-encoding is lossy, and the converter uses a high quality setting to keep the loss hard to see. Screen recordings with flat colors and text survive it well.

Where do WebM files come from?

Browser-based screen recorders, the MediaRecorder API, OBS set to WebM, and video downloaded from sites that serve WebM. All of them decode here.

Jump straight to a conversion

Full Video Converter tool

001 MKV to MP4 Converter

002 MOV to MP4 Converter

003 MP4 to WebM Converter

Explore Our Tools

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Video Converter

Convert video between MP4, MOV, WebM, and MKV. Streams that already fit the new container are copied without re-encoding; the rest are re-encoded to H.264, VP9, AAC, or Opus.

Black and White Video Converter

Convert a color video to black and white using perceptual luminance, with optional auto-contrast, partial desaturation, and inversion. Exports MP4 or WebM with the original soundtrack.

Note to Frequency Converter

Convert a note name to its frequency in hertz, or a frequency to the nearest note with its offset in cents. Set the A4 reference between 390 and 500 Hz, and read the MIDI number, the period, and the wavelength alongside it.

Screen Recorder

Record your screen, one window, or a browser tab as MP4 or WebM, with tab or system sound and your microphone mixed in. Pause and resume, then trim, crop, or compress the recording on the next page.

Blur Video

Blur every frame of a video with a Gaussian blur, and mix the blurred frame back over the sharp one to soften rather than erase detail. The blur scales with the output size, so the preview matches the export. Exports MP4 or WebM with the original soundtrack.

Video Clarity

Raise or lower midtone local contrast in a video to add punch or soften texture, with radius and tonal focus controls. Exports MP4 or WebM with the original soundtrack.

Color Splash Video Effect

Keep one color vivid in a video and turn everything else black and white. Pick the color to keep, then set tolerance, edge softness, and background desaturation. Exports MP4 or WebM with the original soundtrack.

Cross-Stitch Video Effect

Render every frame of a video as cross-stitch embroidery: X-shaped thread stitches in a reduced palette on aida cloth. Set stitch scale, thread colors, and fabric color. Exports MP4 or WebM with the original soundtrack.

Dispersion Video Effect

Break the edges in every frame of a video into particles that drift left, right, up, or down, with a new particle layout on every frame. Set particle amount, travel distance, edge threshold, and direction. Exports MP4 or WebM with the original soundtrack.

Drip Video Effect

Pull the strong edges in every frame of a video into downward paint trails, with new trails drawn on every frame. Set drip length, trail spread, edge threshold, and drip amount. Exports MP4 or WebM with the original soundtrack.

Engraving Video Effect

Turn every frame of a video into an antique engraving: hatch lines that follow the form, crosshatching in the shadows, and etched edges that move slightly on every frame. Set ink and paper colors, exposure, and line density. Exports MP4 or WebM with the original soundtrack.

Expired Film Video Effect

Age a video like expired color film: shadows and highlights drift to opposite casts, blacks fog up, the emulsion mottles, and grain moves on every frame. Set degradation, crossover, fog, mottling, and grain. Exports MP4 or WebM with the original soundtrack.