What is Beatmatching?
Beatmatching is the DJ skill of adjusting the tempo of an incoming track so its beats line up with the track that is already playing, so the two can be mixed without the drums falling out of step.
It has two parts: matching the tempo, usually with the pitch fader, and aligning the phase, so the kick drums land at the same moment. Traditionally, DJs do this by ear in headphones, nudging the incoming record forward or back until it stays locked.
Modern DJ software and controllers offer a sync button that does it automatically using the tracks' analyzed BPM and beat grids. Many DJs still learn manual beatmatching because it helps when grids are wrong or when tracks have live drummers with a moving tempo.
Tracks far apart in tempo are often mixed using half time or double time relationships, or with a cut or effect instead of a long blend.
Put it to work
Find the BPM and key of your tracks before you plan the mix.
Detect Key and BPM