Merge videos

About this tool

Join several video clips into a single MP4. Add up to ten clips from your device or paste links, see a thumbnail and the length of each one, put them in the order you want by dragging (or with the up and down buttons) and press Merge videos. There is no upload, no sign-up and no watermark.

Clips from different phones, cameras or apps rarely match: they have other sizes, frame rates and audio settings. The tool checks every clip and picks the right method automatically. Matching clips are joined instantly without any quality loss. Clips that differ are converted to a common size, frame rate and sound format first, with black bars where a shape does not fit.

Fast join or re-encode: how the tool decides

The tool reads every clip and compares the video codec, picture size, frame rate, colour format, rotation and audio format. If everything is identical, and the format can be stored in an MP4, the clips are joined by copying their data one after another. That takes a moment, uses almost no processing power and keeps the quality exactly as it was.

If anything differs, copying would produce a broken or out-of-sync file, so the tool converts all clips to the same format and joins them in one pass. It also tells you which differences it found. The result is H.264 video with AAC stereo audio at 48 kHz, which plays on practically every device.

Different sizes, shapes and missing sound

When clips have different picture sizes you choose the output size: match the first clip, or 1080p, 720p or 480p. A clip with another shape is never stretched. By default it is fitted inside the frame with black bars; choose Fill (crop) if you prefer the frame to be filled and the edges cut off. A portrait clip joined to landscape clips therefore appears centred with bars at the sides.

If some clips have no sound, silence is added for them so that the audio of the other clips stays in sync with the picture. Clips with different frame rates are converted to one common rate, by default the rate of the first clip, or 24, 30 or 60 frames per second if you choose.

Time and memory

A fast join takes seconds. A re-encode runs on one processor thread inside your browser, so it takes longer for longer videos and bigger pictures; the tool shows a rough estimate before you start and the live speed while it works. On a phone it is several times slower than on a computer, so for a long merge consider choosing 480p or using a computer.

To keep within the memory a browser tab can use, the total size of all clips is limited (see below). Merged results are also easy to pass on: open them in Compress video to shrink the file, or in the Video cutter to trim the joined video.

Limits and tips

• Up to 10 clips per merge. The total size of all clips can be about 600 MB on most desktop computers and about 200 MB on phones and tablets.
• The result is always an MP4. A fast join is about as large as the clips together, and a re-encoded merge is usually smaller.
• Clips with different frame rates, sizes or sound formats are re-encoded, which is slow on a phone. Merging clips that were all recorded on the same device is usually a fast join.
• Very high resolutions (4K) are slow to re-encode. Choose 1080p or 720p as the output size to speed things up.
• Keep the tab open and the screen awake while a long merge runs. You can cancel at any time; your list and settings are kept so you can try again.
• The first run downloads the conversion engine (about 10 MB compressed) and keeps it in your browser's cache.