Metronome markings are given in beats per minute. They can be estimated using a clock with a second hand, but the easiest way to find them is with a metronome, which is a tool that can give a beat-per-minute tempo as a clicking sound or a pulse of light. This Figure 1.68 shows some examples of metronome markings.
Metronomes often come with other tempo indications written on them, but this is misleading. For example, a metronome may have allegro marked at 120 beats per minute and andante marked at 80 beats per minute. Allegro should certainly be quite a bit faster than andante, but it may not be exactly 120 beats per minute.