Time signatures are a very important part of reading and writing music. They tell us everything we need to know about how to count and group notes and which beats we should put emphasis on.
In this guide, we’re going to learn all about time signatures and how to use them in music theory.
What Is A Time Signature?
A time signature is made up of two numbers, one on top of the other and looks a bit like a fraction.
Here are some examples of what a time signature looks like:
We use time signatures to tell musicians how to group musical notes.
For example should we group them in beats of two, three, four or something else.
A time signature also tells us what what kind of beat to count.
I’ll explain what I mean by this shortly but first, let’s look at how we group notes in bars and measures.
Grouping Notes In Bars And Measures
Before we talk about time signatures it’s good to know about why we even need to use them.
It’s all to do with making the notes easier for musicians to read by putting them into groups and which beats we emphasise which affects how the music ‘feels’.
The most common way is to group them is in groups of two, three and fours.
Let’s start by looking at the twelve crotchets below:
Here, you can see they are not grouped at all but now we’ll look at how we group them in bars.
If we wanted to put these 12 crotchets into groups of two, three or four, we can draw vertical lines separating them as shown below.
We call these groups of notes separated by vertical lines bars or in the US they’re referred to as measures.
The vertical lines separating the notes are called bar lines.
Emphasising Certain Beats In A Bar
Not all notes are created equal, some are played a little stronger than others.
We always emphasise the first beat of each bar.
That means we play the note after a bar line a little stronger than the other notes in the bar.
I’ll talk a bit more about strong and weak beats later on.
The Different Types Of Double Bar Lines
There are a few other types of bar lines that we need to know about.
The first one is two thin lines as shown below.
A double bar line like this indicates the end of a section of music. When you reach this type of double bar line it means that you should go on to the next section of music.
The other type of double bar line has a second line which is thicker than the first.
This type of double bar line indicates that this bar is the very last one of the piece of music.
The Two Numbers Of A Time Signature
Now we know a bit more about bars and measures we’ll look at what the two numbers in a time signature mean and how to use them.
What Does The Top Number Represent?
The top number in a time signature represents how many beats there are per bar.
- If the top number is two then there must be two beats in a bar
- If the top number is three then there must be three beats in a bar
- If the top number is four, there must be four beats in a bar
And so on.
What Does The Bottom Number Represent?
The bottom number tells us what kind of beat to count.
For example, we might be counting crotchet beats, or minim beats or quaver beats.
This is best explained with some examples.
The Time Signature 2/4
If we look at the time signature 2/4 below, it means there should be two crotchet beats in each bar.
The top number tells us how many beats per bar (two in this case) and the bottom number tells us what kind of beat (crotchet beats in this case).
But Why Does The Number Four Mean Crotchet Beats?
The number four is used because four crotchet beats are equal to one semibreve.
If the bottom number in the time signature was a two then it would represent minim beats because two minim beats are equal to one semibreve.
If the bottom number was an eight then it would represent quaver beats because eight quavers are equal to one semibreve.
Here are all the bottom numbers in a time signature and their corresponding note value:
- 1 = Semibreve / Whole note (these are very rare, you won’t see these)
- 2 = Minim / Half note
- 4 = Crotchet / Quarter note
- 8 = Quaver / Eighth note
- 16 = Semiquaver / Sixteenth note (also quite rare)
The Time Signature 3/4
The time signature 3/4 means there should be three crotchet beats in a bar.
Again, the top number tells us how many beats per bar (three in this case) and the bottom number tells us what kind of beat (crotchet beats as it’s a number four).
The Time Signature 4/4
The time signature 4/4 means there are four crotchet beats in a bar.
The top number tells us how many beats per bar (four in this case) and the bottom number tells us what kind of beat (crotchet beats as it’s a number four which represents crotchets).
Another time signature you might see is one that looks like the letter C.
This stands for common time and is exactly the same as 4/4 and so has four crotchet beats per bar.
Using Combinations Of Different Notes
But we don’t only have to use only crotchets if the bottom number in the time signature is a four.
We can use longer or shorter notes too.
The only rule is that they have to equal the number of beats in the time signature.
For example any of these are correct:
Just remember that every single bar should always add up to the correct number of beats indicated in the time signature.
Regular Time Signatures
There are a few different ways to categorise time signatures, the main two are regular (or common) and irregular time signatures.
A regular time signature is defined by having a top number that is divisible by two, three or four.
That means that the number of beats in a bar is going to be two, three or four.
For example, the time signature 3/4 has three crotchet beats in a bar and so is a regular time signature because three can be divided by three.
Or another example would be the time signature 12/8 which has four dotted crotchet beats and so is divisible by two, three or four.
But 5/8 which has five quaver beats in a bar has a top number five which can’t be divided by two, three or four and so is an irregular time signature (more about those soon).
Duple, Triple and Quadruple Time
We can further categorise regular time signatures into three more groups:
- Duple time
- Triple time
- Quadruple time
These are referring to whether a regular time signature can be divided by two, three or four.
Duple time is where we will have two main beats in a bar. An example of this would be 2/4 which has two crotchet beats in a bar or 2/2 which has two minim beats in a bar.
Triple time is where we have three main beats in a bar. An example this would be 3/4 which has three crotchet beats in a bar or 3/8 which has three quaver beats in a bar.
Quadruple time is where we have four main beats in a bar. An example of this would be 4/4 which has four crotchet beats in a bar or 4/2 which has four minim beats in a bar.
Simple And Compound Time Signatures
Another way to group time signatures is into either simple or compound. There is an easy way to remember the difference.
A simple time signature has a top number that’s either a 2, 3 or a 4.
A compound time signature has a top number that’s either a 6, 9 or 12.
To get a better idea of how these work I’ve put together some time signature charts to download over here.