Another challenge when reading a chart or lead sheet centers on tempo changes. Tempos are usually consistent within a given piece of music; however, it is not uncommon to find changes during some tunes. Having a tempo change during a song presents certain problems, especially when that change is communicated to you through a written chart. Usually the change will be written exactly as it occurs. If you are lucky, a metronome marking may indicate an exact value. This will be written with a quarter note placed above the staff with an equal sign and a numerical value. Theoretically, if the tempo is increased to twice as fast, the new beats per minute (BPM) value will require multiplying the initial numerical value by two. For example, if you are at 60 BPMs and the music asks you to play “double time,” you will now play at 120 BPMs.

Unfortunately, tempo indicators are not always that precise. Since traditional (Italian) tempo marking have a range of approximate values, it can be difficult to pin down exactly how fast any tempo should be let alone how fast or slow the new section should be. This is just something that you have to get used to.

Tempo is often best viewed as a relative concept. In other words, if you are to move from one tempo to another, the second tempo may be based on the initial tempo in a relative way. It can still be exactly twice as fast, but you may not have an absolute value for either tempo. Furthermore, many tempo changes are fairly arbitrary. In some tunes, you simply get faster, as in the change from moderato to allegro, or slower, as in the change from andante to adagio. In these cases, you must use your best judgment.

If you are making these changes as a band, it helps to follow the drummer. You may also designate one musician to be the leader. Sometimes this person even conducts the change (similar to classical music conducting). This is not commonplace though. Usually the leader will communicate the tempo or feel change through exaggerated body language and playing gestures.

The two most common types of tempo change keep the relationship between the two different tempos at a fixed, predictable ratio. As mentioned just previously, “double time” just means to play twice as fast. Likewise, “half time” means to play half the speed. In order to pull these tempo shifts off with accuracy, you must conceive of them properly. When making such changes, your knowledge of note values and note relationships must guide you into the next tempo.

For example, if you have “double time” indicated in the chart, simply turn your current quarter-note value into eighth notes. Since eighth notes are twice as fast as quarter notes to begin with, you can use them as the basis for reformulating your tempo. For half time, move in the opposite direction and turn quarter notes into half notes. Since half notes are half the speed (or twice the length) of your initial quarter-note pulse, they provide the perfect basis for reformulating your new quarter note speed.