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Video to MP4 for Better Playback Everywhere

Changing a video's format to MP4: why the codec matters

Convert a supported video such as MOV, WebM or MKV into an MP4 file. Choose the video and audio codecs, resolution and quality settings for the destination device. MP4 is a container: compatibility also depends on the codecs inside it. H.264 video with AAC audio is a practical starting point for broad playback support. Check the exported clip before replacing your original.

Cost: Free to use. File size and usage limits apply.

How to convert a video to MP4

  1. Upload one video

    Click Upload a video to convert to MP4 or drop the file on the preview. MP4, MOV, MKV, WebM, AVI, M4V, MPEG/MPG and OGV files up to 200 MB are accepted. Videos you uploaded or created in other tools on this site are listed under Uploads.

  2. Check the codecs

    Under Codecs, Video codec starts at h264 and Audio codec at aac. That pair plays on the widest range of browsers, phones and TVs. Switch to copy when the source already uses codecs that MP4 can hold.

  3. Change size or quality only if you need to

    Open Optional resize for resolution, frame rate, CRF and bitrates. Its defaults keep the source resolution and frame rate.

  4. Convert

    Click Convert to MP4. The job runs on our server and the progress bar moves from Queued to Processing. Reset below the button restores all default settings.

  5. Check and download

    Play the result in the preview, check the file size shown on the result card, then click Download. Continue editing keeps the same source so you can try other settings.

Settings explained

Everything except the two codec menus is under Optional resize, which starts at Original resolution, the source frame rate, CRF 23 and empty bitrate fields.

Video codec
h264 (H.264) is the default and the safe choice for browsers, phones, TVs and editing software. h265 (HEVC) needs less data for a similar picture, but it encodes several times slower and not every browser decodes it. mpeg4 (MPEG-4 Part 2) is only for very old players.
copy (video)
Moves the original video stream into the MP4 without re-encoding. There is no quality loss in the copied video stream, and the job avoids video re-encoding. The total file size can change with the container, audio, retained tracks and metadata. It works when the source video is H.264, H.265, MPEG-4 Part 2 or AV1. For other codecs, such as VP8 or VP9 from WebM, the tool encodes with h264 instead. A resolution, FPS value or video bitrate also switches to h264, because those changes require re-encoding.
Audio codec
aac is the standard audio codec for MP4, and mp3 is valid too. copy keeps AAC or MP3 audio unchanged and converts anything else, such as Opus, AC-3 or uncompressed PCM, to AAC. none removes the sound.
Resolution
Original keeps the source size. The presets scale the video to a standard quality level while keeping its aspect ratio: 360p fits it into 640×360 px, 480p into 854×480 px, 720p into 1280×720 px, 1080p into 1920×1080 px, 1440p into 2560×1440 px and 4k into 3840×2160 px. Use Custom for an exact frame size. A preset larger than the source upscales: the file grows without gaining detail.
Width and Height (Custom)
In pixels. Fill in only one field and the other side is calculated from the aspect ratio: Width 720 turns a 1080×1920 px phone clip into 720×1280 px. Fill in both only when you need exactly that frame. Odd numbers are rounded down to even ones, up to 7680 px wide and 4320 px high.
FPS
Empty keeps the source frame rate. Enter a frame rate from 1 to 120 fps, for example 30 or 29.97. Going from 60 to 30 fps saves space; raising the frame rate only repeats frames and does not make motion smoother.
CRF
Constant quality from 0 to 51; it has no effect with copy. Lower numbers mean better quality and bigger files; the default is 23. As a rule of thumb, around 18 looks visually lossless with H.264, and h265 at 28 looks roughly like H.264 at 23 in a smaller file.
Video bitrate
Encodes at a fixed average data rate instead of the CRF quality target, which makes the size predictable. Enter kilobits per second with a k, for example 2500k, or megabits with an M, such as 4M.
Audio bitrate
For aac and mp3, for example 128k or 192k. Empty means 128 kbps for stereo sound. It has no effect with copy or none.

Recommended settings by source

MP4 only wraps the streams; the codecs inside decide where the file plays. These starting points cover the most common sources.

MOV from an iPhone or camera

Try copy for video and audio first: H.264 or HEVC video is rewrapped without loss, and audio MP4 can't hold, such as the PCM sound of many cameras, is converted to AAC. Choose h264 when the MP4 has to play on older devices that don't decode HEVC.

MKV download

copy for both keeps H.264 or HEVC video and AAC or MP3 audio untouched and turns AC-3, DTS or FLAC sound into AAC. Only one audio track is kept, normally the one marked as default, so check the language.

WebM screen recording

Keep h264 and aac, because VP8 and VP9 video has to be re-encoded for this MP4. Small text in tutorials stays sharper at a CRF of 18 to 20.

Old AVI, MPEG or OGV file

Keep the defaults. AVI files with Xvid or DivX video could be copied as MPEG-4 Part 2, but most browsers can't play that codec, while H.264 plays almost everywhere.

Formats and limits

Input formats
MP4, MOV, MKV, WebM, AVI, M4V, MPEG/MPG, OGV
Output format
MP4 with H.264, H.265 or MPEG-4 Part 2 video (or the copied source stream) and AAC or MP3 audio. For WebM use Video to WebM; for MOV, MKV, AVI and other containers use Video Converter.
Maximum file size
200 MB per video
Files per job
1
Kept from the source
The full length, one video track and one audio track, and the resolution and frame rate unless you change them. Subtitle tracks and extra audio tracks are dropped. Metadata tags such as the title and recording date are carried over.
Processing
On our servers with FFmpeg. A job can run for up to 15 minutes, so h265 on a long 4K clip may not finish. No AI or third-party service is involved.
Watermark
None
Storage
Uploads and results are deleted automatically after 48 hours for guests and after 30 days for free accounts. Paid plans can keep files longer.

Frequently asked questions

Why is the MP4 larger than my original video?

The source was probably compressed more efficiently, for example H.265 from a phone or VP9 from a WebM file. H.264 at CRF 23 needs more data for the same picture. Use copy if the source codec allows it, raise CRF to 26–28, pick h265 or lower the resolution. For a hard limit in MB, Compress Video can aim at a target size.

Does converting to MP4 reduce quality?

Not with copy, as long as the source codecs fit MP4: the streams are moved into the new container unchanged. If they don't fit, or with any other codec, the video is re-encoded and loses some detail. At the default CRF 23 the loss is hard to spot in normal footage, but it adds up if you convert the same file repeatedly, so keep your original.

Which codecs can an MP4 file contain?

MP4 can hold several video codecs, including H.264, H.265, MPEG-4 Part 2 and AV1, and audio codecs such as AAC and MP3. This tool encodes to H.264, H.265 or MPEG-4 Part 2 and can copy AV1 streams unchanged. VP8 or VP9 video and Opus or Vorbis audio from WebM files are converted.

My MP4 still doesn't play on my TV or phone. What should I change?

Look at the codecs, not the file extension. With copy, the original codec stays in the file, and h265 or mpeg4 aren't decoded by every device. Convert again with h264 and aac, the pair with the widest support. Older TVs may also need a resolution of 1080p or lower.