A guide to understanding time signatures

Time signatures are important elements of playing and writing music. Here is a beginner's guide to the principles behind musical time signatures.

What is the time signature?

The term 'time signature' refers to the two numbers located at the beginning of a piece of music. The top number tells musicians how many beats there are in each bar, or sub-division of the music, whilst the bottom figure refers to the type of note that is being given one count.

Simple time

Some of the most commonly used time signatures are in what is called simple time. Simple time refers to time signatures in which the beats are grouped in two or four. The most commonly seen time signature is 4/4, also known as common time. In common time, the top number is 4, which tells us there are four beats in each bar. The 4 on the bottom tells us that a crotchet (also known as a quarter note) receives one beat. Therefore, the time signature 4/4 tells musicians that each bar contains notes to the value of four crotchet beats. If the time signature is 3/4, a crotchet will again be worth one beat, but this time there will be only three beats per bar.

Compound time

The same rules apply to compound time signatures. However, there are a couple of key differences. The first is that, unlike simple time, notes are grouped in three. The second difference refers to the number on the bottom of the time signature. Compound time signatures most commonly feature 8 as the bottom digit, meaning that a quaver (or eighth note) now receives one count instead of a crotchet. (A bar of 6/8 for example, will feature notes to the value of six quaver beats.) It is important to note that when changing from simple to compound time, all note values will double. For example, a quaver worth half a count in simple time is worth one count in compound time, whilst a one beat crotchet is worth two if used in 6/8. A dotted crotchet in simple time will receive one and a half beats, but is worth three in compound, and so on.

Odd time signatures

Many twentieth and twenty-first century pieces feature odd time signatures, and some are without a time signature at all. As long as a musician is fluent in his or her note values, then unusual key signatures are easy to understand. For example, if the time signature is 5/16, the musician would know that a
semi-quaver (sixteenth note) receives one count, and that each bar features five beats. Thus, 5/16 = five semi-quaver beats in each bar.