How it works
It listens for the hits. Every drum, pluck and chord stab makes a small spike in the sound, and the finder measures how evenly those spikes repeat. Then it compares that tempo with half and double it, and picks the one songs are most often in.
It’s the same tempo detection as DOT, Plastic’s recorder for the Mac, so the two always agree. It runs on your computer, in this page: your file is never uploaded.
Why it sometimes says “or 75”
Half time and double time are the same pulse counted two ways. A trap beat at 140 BPM also feels like 70, and a ballad at 80 can be counted at 160. When both readings fit almost equally well, the finder shows the other one too. Pick the one that matches how you count the song.
When it finds no tempo
Some music has no steady beat for it to lock on to: a pad, an ambient intro, a piano played freely. Very short files have the same problem, because it needs at least two seconds of sound. If your song starts slowly, cut off the intro and try the part where the drums come in.
Need the key and chords too?
DOT records whatever your Mac is playing, from a video, a preset demo or a friend’s session, and gives you its key, tempo and chords. You drag the clip straight into your DAW, and the chords come out as MIDI.
Questions
Is my song uploaded anywhere?
No. The finder runs in your browser. Your file is read on your computer and never sent to us or anyone else.
Which files work?
MP3, WAV, AIFF, M4A and FLAC all work. Video files with sound, like MP4 and MOV, usually work too.
How accurate is it?
On 128 of Kai Williams’s own beats it named the exact BPM 88% of the time, and on 32 of Kai’s released songs 81%. Most of the rest were half or double time, which is why the finder shows the second reading when it’s close.
Why does it only listen to the first two minutes?
Most songs keep one tempo, and two minutes is plenty to measure it. If yours changes tempo, cut the part you need and drop that in instead.
Can it find the key?
Not yet. For now, DOT finds the key and chords of anything your Mac plays.
Is there a limit?
No sign-up, no limit and no watermark. It’s free.