How to Convert Video to MP4 Without Losing Quality (Free)

To convert a video to MP4, open it in a converter, choose MP4 as the output and download the new file. With the free WoowTools video converter this takes seconds for most MOV, WebM and MKV files, because video that is already H.264 is copied into the MP4 container instead of being re-encoded, so nothing is lost.

This guide explains when a conversion is instant and lossless and when it has to re-encode, which settings to pick, and how to do the same in VLC, HandBrake or FFmpeg. It ends with fixes for the most common playback problems.

Why convert a video to MP4?

MP4 with H.264 video and AAC audio plays almost everywhere: iPhone and Android, Windows and Mac, smart TVs, WhatsApp, YouTube and every web browser. Other formats often do not. A WebM may not open in an older phone gallery app, an MKV from OBS will not upload to some platforms, and an iPhone MOV can refuse to play on Windows.

Converting to MP4 fixes those problems in one step. It also makes the file easier to edit, because nearly every video editor imports MP4 without extra codecs.

How to convert a video to MP4 online (step by step)

Converting a video to MP4 online takes four clicks in the browser converter, and the file never leaves your computer.

1. Open the video converter.
2. Drop your video onto the page. MP4, MOV, WebM and MKV files are supported.
3. Choose MP4 as the output (H.264 video and AAC audio, plays everywhere). Pick WebM instead if the video is only for a website.
4. Choose High quality (close to the original, larger file) or Balanced (good quality, smaller file). This only matters when the video has to be re-encoded.
5. Read the line under the settings. It tells you whether the video will be copied without re-encoding or converted, and which codecs it found.
6. Click Convert to MP4 and download the file.

Because the conversion runs on your device, a large file does not have to upload first, and private videos stay private.

Does converting to MP4 lose quality?

Converting to MP4 loses no quality when the video is already H.264, because the video stream is copied into the new container unchanged. Only other codecs, such as H.265 (HEVC) from newer iPhones or VP9 from WebM files, have to be re-encoded, which costs a little detail.

Your file	Video codec	What happens when you convert to MP4
OBS or screen recorder MKV	Usually H.264	Copied: instant, no quality loss
MOV from a camera or older iPhone	Often H.264	Copied: instant, no quality loss
MOV from a newer iPhone (High Efficiency)	H.265 (HEVC)	Re-encoded to H.264 so it plays everywhere
WebM from a website or browser recording	VP8 or VP9	Re-encoded to H.264
MP4 that will not play somewhere	H.265 or another codec	Re-encoded to H.264

Audio follows the same rule. AAC and MP3 audio are copied into the MP4; other audio, such as Opus from a WebM, is converted to AAC at 160 kbps on High quality or 128 kbps on Balanced.

Which settings should you choose?

Pick MP4 for anything you will share, play on a phone or TV, or upload to social media. Pick WebM only for video that will play on a web page you control, since every modern browser supports it and the files are small.

For quality, start with High quality. Switch to Balanced when the file is too large to send; if you need a specific size, such as 25 MB for email, use the video compressor instead, which works out the bitrate for you.

Converting MOV, WebM and MKV to MP4

Each source format has its own dedicated page that locks the output to MP4 and explains that format's quirks:

• MOV to MP4: for iPhone and camera videos that will not open on Windows or Android. Our MOV to MP4 guide covers iPhone settings.
• WebM to MP4: for browser recordings and downloaded web videos that apps refuse, explained step by step in the WebM to MP4 guide.
• MKV to MP4: for OBS recordings and other Matroska files. Our guide on how to convert MKV to MP4 covers the OBS remux setting.

How to convert a video to MP4 with VLC, HandBrake or FFmpeg

If you prefer a desktop program, three free tools do the job:

• VLC: open Media, then Convert / Save, add the file, click Convert / Save, choose the profile "Video - H.264 + MP3 (MP4)" and start. VLC re-encodes, so it is slower than a copy.
• HandBrake: open the video, choose the Fast 1080p30 preset (MP4, H.264), set the destination and click Start Encode. Good for batches, always re-encodes.
• FFmpeg: ffmpeg -i input.mov -c copy output.mp4 copies the streams without re-encoding when the codecs fit MP4. If that fails, ffmpeg -i input.mov -c:v libx264 -c:a aac output.mp4 re-encodes to H.264 and AAC.

The browser converter does the codec check for you and copies whenever it can, which is why it is often faster than desktop software.

Common problems after converting to MP4

• The MP4 has no sound. The original audio is in a format the browser cannot decode, such as DTS or AC-3 from some MKV files. The converter tells you when it had to save the video without sound; convert that file in HandBrake or FFmpeg instead.
• The file got bigger. A re-encode at High quality can be larger than a heavily compressed original. Choose Balanced, or use the compressor with a target size.
• The file type is not supported. The converter reads MP4, MOV, WebM and MKV. For an AVI or a very old format, use HandBrake or FFmpeg.

Need audio only, or a GIF?

To keep just the soundtrack, convert the video to MP3 with MP4 to MP3. For a short looping clip without sound, make an animated GIF with the GIF maker.

Convert your video now

Drop your file into the free video converter, choose MP4 and download a version that plays on every phone, computer and app, usually in seconds and without losing quality.

Frequently asked questions

How do I convert a video to MP4 for free?

Open a free browser converter, drop in the video, choose MP4 and download the result. The WoowTools video converter handles MOV, WebM and MKV and runs on your device, so nothing is uploaded.

Can I convert a video to MP4 without losing quality?

Yes, when the video is already H.264: the stream is copied into the MP4 container unchanged. H.265, VP8 and VP9 videos must be re-encoded, which costs a little detail.

Why does my iPhone video need converting?

Newer iPhones record in H.265 (HEVC) by default, which some Windows PCs, Android phones and websites cannot play. Converting re-encodes it to H.264 inside an MP4, which plays everywhere.

Is MP4 or WebM better?

MP4 is better for sharing, phones, TVs and social media because it plays almost everywhere. WebM is a good choice only for video embedded on a website you control.

Why does my converted MP4 have no sound?

The original audio is probably DTS or AC-3, which browsers cannot decode. Convert that file with HandBrake or FFmpeg, which can turn the audio into AAC.