Split video, into parts, in your browser.

To split a video, choose where the cuts go and the page saves each part as its own file. You can split a video into equal parts, into parts of a set length such as 60 seconds, or at times you type. Fast cut copies the video without re-encoding, so there is no quality loss and a long file takes seconds. Exact cut re-encodes each part and cuts to the frame. Everything runs in your browser, so the video is never uploaded.

How to split a video into parts

1. Drop a video on the box, or click to choose one. MOV, MP4, WebM and MKV files that your browser can play work.
2. Under Split, pick Equal parts and set the Number of parts, or By length and set the Length of each part (seconds), or My marks and type times in Cut at these times, such as 30, 1:15, 2:40.5. Cut at the playhead adds the time you are watching (press C).
3. Pick Fast cut or Exact cut, choose Save as, and decide whether to keep the sound.
4. Read the list of parts and the colour bar. The times are the real ones the files will have.
5. Press Split into N parts. Each part gets its own Download button, and Download all as a ZIP saves them together. Play checks a part first.

Fast cut and key frames

A video is stored as key frames, which hold a whole picture, and the frames between them, which only hold changes. A copy can only begin at a key frame, because the frames after it need it. So Fast cut moves each cut back to the key frame at or before it. The parts then meet at those key frames, with nothing missing between them. The list shows the moved times, and a note says how many moved.

Here is a 30 second test clip with a key frame every 2 seconds, split into 4 equal parts. Equal cuts would be at 7.5, 15 and 22.5 seconds. Fast cut moved them to 6, 14 and 22, so the parts were 6, 8, 8 and 8 seconds. The picture in each file measured exactly that, and the frame counts of 180, 240, 240 and 240 added up to the 900 frames of the original. Exact cut kept the cuts where asked: four parts of 7.5 seconds and 225 frames each.

When the key frames are far apart

A video made with default settings may have key frames only every ten seconds or so. A 20 second test clip had them at 0 and 10.4 seconds. Asking for 4 parts with Fast cut gave 2, because three cuts landed on the same key frame, and the note said so. For equal parts of a video like that, use Exact cut. The page tells you how far apart the key frames are, above the list of parts.

With some files, one frame at a cut shows at the end of one part and at the start of the next, because the frames before a key frame need it to be drawn. On that 20 second clip the two parts added up to 20.042 seconds, one frame more than the original. Exact cut does not do this.

Lengths and sound

AAC sound is stored in blocks of about 21 milliseconds, so a part's sound can run up to about 0.02 seconds longer than its picture. In the test above the first part read 6.016 seconds as a file, where its picture was 6.000, and the sound and the picture both started at zero. Switch off Keep the sound for a silent video.

Common problems

• If the browser cannot play the file, it cannot split it. Change it to a standard MP4 with the video converter first.
• Very long videos split into many parts need memory, since each part is built in the page. Use fewer parts, or trim the video first with the video trimmer.
• The most parts you can make at once is 200. Choose a longer length if you hit it.
• If the Save as type you chose cannot hold your video as it is, for example WebM for an H.264 file, the page says so and re-encodes the parts like Exact cut. Choose Same as the original to copy.

To put parts back together, use the video merger. To make a part smaller, use the video compressor.