The short answer
Open the video in the tool below, then press Choose music and pick an audio file. Under Video's own sound choose Replace or Mix with music. Set Music starts at, and if the song has a long intro, Skip the start of the music. Adjust Music volume and, when mixing, Video sound volume. Choose a Fade out at the end and press Add music. When it is done, check the result and download it.
The music can be an MP3, M4A, AAC, WAV, OGG, Opus or FLAC file, or another video whose sound you want to use. The result keeps the format of the video and always has exactly the length of the video.
Try it here: Add Music to Video
Open the full tool pageReplace or mix
Replace throws away the video's own sound and keeps only the music. It suits holiday clips, product shots, slideshows and time lapses, where wind, traffic or chatter would only distract. Mix with music keeps both sounds and lets you balance them with the two volume sliders.
For speech with music underneath, a good start is the video sound at 100% and the music at 20 to 30%. Play the preview of the original to judge how loud people are speaking, save once, listen to the result and adjust if the music still covers the words. Both sliders go from 0 to 200%, so a quiet recording can also be raised.
| Video | Mode | Video sound volume | Music volume |
|---|---|---|---|
| Holiday or travel clip | Replace | Not used | 100% |
| Talking video, vlog, tutorial | Mix with music | 100% | 20 to 30% |
| Event with some ambience | Mix with music | 50 to 70% | 70 to 100% |
| Quiet phone recording | Mix with music | 150 to 200% | 20 to 40% |
Timing the music
Music starts at sets the point in the video where the music begins. The easiest way is to play the video, pause where the music should come in, for example after an opening line, and press Use current time. Skip the start of the music works on the song itself: it jumps over a long intro so the song begins at the chorus or the beat you like.
A note under the options tells you how the lengths fit. A song shorter than the remaining video repeats from its beginning if Repeat the music if it is shorter than the video is ticked; otherwise it simply stops and the rest of the video is silent, or keeps its own sound when mixing. A song longer than the video is cut where the video ends, and the note says how much of it fits.
Ending softly with a fade out
A song that stops in the middle of a bar sounds like a mistake. Fade out at the end lowers the music gently over the last seconds. You can choose None, 1 s, 2 s, 3 s or 5 s. The fade is applied to the music at its own end: normally that is the end of the video, but if the music stops earlier because repeat is off, it fades out where it stops.
Only the music fades; when mixing, the video's own sound keeps its level until the end. Two or three seconds suits most clips, five seconds suits slow, calm music.
Quality, loudness and formats
The picture is copied without re-encoding, so it keeps its full quality and even a long video is done quickly. Only the sound is created again: AAC in MP4 and MOV, Opus in WebM and MKV, which are the formats phones, computers and video sites expect.
When the music and the video sound together, or a volume above 100%, would get louder than a file can hold, the tool turns the whole mix down a little. Nothing clips or crackles, and the balance you chose between the two stays the same.
Music rights
Owning a song or a streaming subscription usually does not give you the right to publish it in a video. Platforms can mute or block videos that use protected music. For anything you post publicly, use music you made, royalty free music with a license that allows video use, or tracks from the music libraries that video platforms offer for their own uploads. For private videos shared with family, this matters much less.
Adding music with built in apps
iMovie on iPhone, iPad and Mac and Clipchamp on Windows can put music under a clip, and many phone gallery apps offer a soundtrack when you make a highlight video. These editors usually encode the whole video again when you save.
The browser tool is handy when you want the picture untouched, need the exact song from your own files, want to use the sound of another video, or work with WebM and MKV files.
Common problems and fixes
- The music drowns out the voices: choose Mix with music and lower Music volume to 20 to 30%, or raise Video sound volume.
- Your browser cannot create the sound for this format: Firefox cannot encode AAC, which MP4 and MOV need. Use Chrome, Edge or Safari.
- The music file cannot be read: convert it to MP3 first, then choose it again.
- Nothing of the music is left after the skipped part: Skip the start of the music is longer than the song. Skip less.
- The music stops before the video ends: tick Repeat the music if it is shorter than the video.
- The file is too long to process in the browser: use a shorter video or trim the music first.