Press "Start" on a stop watch precisely as the song begins playing. Start the song at the very beginning of the first verse if the song begins with an extended instrumental intro, experimental riff or vocal sample, .
Begin counting the beats of the song. Some songs make this process easy by using one kick drum sound, which is the low-frequency bass drum that sets the pace of the percussion, for each beat in the measure. Other songs make this process more difficult. To count the beats, consider the pace at which you would clap your hands or tap your toes. Follow the drum beat, if possible. If no drums are present, or if the drumbeat is irregular, imagine a steady drum beat, and count the beats.
Stop counting when the stopwatch reads exactly 15 seconds. If the song uses a traditional 4/4 time signature, which is the most common time signature in popular music, there are approximately between 20 and 40 beats.
Multiply the number of beats by four to determine the BPM of the song. For example, if 25 beats are counted in 15 seconds, the song tempo is 100 beats per minute. If 40 beats are counted, the tempo is 160 beats per minute.