Pick the part of a song or recording you want to repeat, hear it loop seamlessly with a smooth crossfade at the joint, then repeat it a set number of times or until it fills a target length. Download the result as WAV or MP3. Your audio never leaves your device.
Last updated:
A
B
Length of the result
Your loop is ready
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How to use the Audio Looper
Add your audio: drop a file on the box or click to choose one. A demo groove is loaded so you can try it right away.
Select the loop: drag across the waveform, drag the handles, or type the start and end times. With a known tempo, enter the BPM and pick a number of bars.
Listen: press Play loop to hear the region repeat. Raise the crossfade or snap to zero crossings if you hear a click or bump at the joint.
Choose how long: repeat the loop a number of times, or fill a duration. Optionally keep the intro and outro and fade out the end.
Create and download: press Create looped audio, check the result in the player and download it as WAV or MP3.
How a seamless loop is built
A loop is a region from point A to point B that plays again and again. If you simply glue copies of it together, the last sample before B jumps straight to the first sample at A. Unless both happen to have the same value, the waveform has a sudden step, which you hear as a click or a thump, and any reverb tail or sustained note is cut off.
The looper hides that joint with a crossfade. At every repeat, the last part of the loop (ending at B) fades out while the audio leading into A fades in over the same time, so the sound that naturally comes before A is already playing when the loop restarts. The orange stripes on the waveform show the audio that is blended in. If there is no audio before A, the looper uses the audio right after B instead, and if the loop covers the whole file it overlaps the loop end with its own start.
Equal-power crossfade: the outgoing part is multiplied by cos(t × 90°) and the incoming part by sin(t × 90°), where t goes from 0 to 1. Because cos² + sin² = 1, the combined loudness stays steady for typical music.
Linear crossfade: the gains are 1 − t and t. They add up to exactly 1, which is best when both parts are almost identical, such as a held note, a drone or room tone.
Choosing loop points by tempo
Music loops sound natural when they last a whole number of bars. In 4/4 time one bar has four beats, so its length in seconds is 4 × 60 ÷ BPM:
Tempo
1 beat
1 bar
2 bars
4 bars
8 bars
80 BPM
0.750 s
3.000 s
6.000 s
12.000 s
24.000 s
90 BPM
0.667 s
2.667 s
5.333 s
10.667 s
21.333 s
100 BPM
0.600 s
2.400 s
4.800 s
9.600 s
19.200 s
120 BPM
0.500 s
2.000 s
4.000 s
8.000 s
16.000 s
128 BPM
0.469 s
1.875 s
3.750 s
7.500 s
15.000 s
140 BPM
0.429 s
1.714 s
3.429 s
6.857 s
13.714 s
Place A exactly on a downbeat (zoom your eyes to the first kick drum hit, or click the waveform to listen from a point), enter the tempo, choose the number of bars and press Set length from BPM. If you do not know the tempo, measure it first with a BPM finder.
Tips for clean loops
For music, a crossfade of 10–50 ms removes clicks without smearing drum hits. Use 200–500 ms for ambience, rain, crowd noise or drones.
Snap to zero crossings moves A and B (by at most 20 ms) to a point where the wave rises through zero, which helps when you want little or no crossfade.
To make background music longer for a video, keep the intro and outro and fill the exact duration of the video; the loop is repeated in the middle and the song still starts and ends naturally.
Listen to the joint with Play loop before exporting: the preview uses exactly the same crossfade as the downloaded file.
Frequently asked questions
Is my audio uploaded?
No. The file is decoded with your browser's Web Audio API and the loop is built from its samples on your device. Nothing is sent to a server.
Why do I hear a click where the loop restarts?
A click happens when the waveform jumps from one value to a very different one at the joint. Turn on a crossfade of 10–50 ms, or press Snap to zero crossings so both loop points sit where the wave crosses zero. For music, a loop that starts and ends exactly on the beat sounds the most natural.
How does the crossfade work?
At every joint the end of the loop fades out while the audio just before the loop start fades in over the crossfade time, so the sound blends instead of cutting. Equal-power curves (sine and cosine) keep the loudness steady for most music; linear curves suit very similar or sustained sounds.
How do I loop a song for exactly 1 hour?
Choose Fill a duration and type 60:00. The looper repeats the region as often as needed, trims the result to exactly the target length and can fade out the last seconds. Results are limited to 60 minutes to stay within browser memory.
How do I set the loop length from the BPM?
One bar of 4/4 music lasts 4 × 60 ÷ BPM seconds, so at 120 BPM one bar is 2 seconds and four bars are 8 seconds. Enter the BPM, pick the number of bars and press Set length; the end point is placed that far after the start.
Which format should I download?
WAV is lossless and best if you will edit the file further, but it is large (about 10 MB per minute in stereo). MP3 at 192 kbps is about 1.4 MB per minute and plays everywhere.
Will the output keep the original quality?
Yes. Samples are copied directly from the decoded audio at your device's sample rate, only the crossfade zones are mixed. Exporting to WAV keeps 16-bit quality; MP3 adds normal lossy compression.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.