What is a Time Signature?
All music is divided into measures, or short units that contain a set number of or “counts,” and
You’ve probably heard musicians counting off 1-2-3-4, 1-2-3-4, in which case the set of four beats is a single measure.
This “measure” structure is the backbone for the song’s rhythm. But not all measures are the same! While most have four beats, they can have any number at all. For example, a waltz has three beats per measure, so you would count “1-2-3, 1-2-3” as you tap along.
Parts of Time Signature
The most common time signature is 4/4, which has four notes, each marked by a quarter note. This is the standard way of writing time signatures:
- The first number tells you how many beats per measure
- The second number tells you what kind of symbol represents a single beat (this only matters for reading music)
- The second number can only be a multiple of two – usually 2, 4, or 8 – because those are the “note” symbols that exist in Western music (half, quarter, eighth, etc.)
4/4: four beats per measure. Each beat is represented by a quarter note (this is also called “common time”)
3/4: three beats per measure. Each beat is represented by a quarter note
6/8: six beats per measure. Each beat is represented by an eighth note
The first number is the most important, since it tells you how many beats per measure there are going to be. The second number only matters for reading music, but makes no difference to how the music sounds.
Time Signature vs. Tempo
People sometimes confuse time signature with tempo, but they’re actually very different. Time signature is the pattern of beats — how many beats you get per measure. Tempo is the speed of those measures. So time signature tells you whether you’re counting 1-2-3-4 or 1-2-3. But tempo tells you how fast you should be doing that count.
Here are a couple of easy examples:
Notice how the first example has three quarter notes in a measure, while the second has just two. That matches the 3/4 and 2/4 time signatures for the songs.
In the following song, the singer helpfully counts off the time signature at the beginning: “1-2-3, 1-2-3.” So you know it’s a “3-count” time signature. If the song was written down, it would probably use quarter notes to represent each count, which means it would be 3/4 time!
You’ve probably heard plenty of songs with a 3-count, and most of the songs you know are probably 4-count! But what about the other, more unusual counts? These are much less common, and can be very difficult to play, but when you learn to recognize them you’ll be doubly impressed by the songwriters’ creativity in using such a difficult time signature.
Let’s start with a 5-count time signature. Howard Shore used one of these in the Isengard Theme from the Lord of the Rings soundtrack. Listen to the drums in the background and count along: you’ll notice that the pattern is broken into 5 beats. This unusual time signature is part of what gives the tune its plodding, mechanical energy.
When this time signature is written, it’s usually “5/8,” with eighth notes representing a single beat. If eighth notes represent a single beat, then quarter notes would represent two beats. So in this example we see a quarter note (2 beats) followed by three eighth notes (3 beats), 2+3=5.
You can hear an even stranger time signature in this song by the heavy metal group Alice in Chains. The opening riff is deceptively simple, and at first you might not notice there’s anything odd about the beat. But if you try counting along, you may quickly get lost! That’s because the main riff has a 7-count time signature. Just like with the Isengard Theme, this gives the song a powerful, but dark, sound.
7-count time signatures also usually use eighth notes. Here’s an example of 7/8 time:
Why Are Time Signatures Important?
It’s probably obvious why the first number matters: you have to know how many beats are in a measure so that you know the basic backbeat of a song. Three-count songs have a very different beat from four- or seven-count songs.
But what about that second number? Why don’t composers just standardize and always use a quarter-note to represent a single note, the way they do in the more common 4/4 and 3/4 time signatures?
Unfortunately, there’s no simple answer to this question. This is one of those early traditions that have been maintained in music notation over the centuries, and composers have found their own reasons for changing the second number in a time signature.
One of the reasons might be that it helps keep the page clear. For example, you might have four beats per measure in a relaxed, gentle-sounding song with a lot of half-note and whole-notes. In other words, you’d have four beats per measure but most of them would not be played (you might play a note on the “1” count and hold it all the way through the measure). On the other hand, you might have a frantic, high-energy song where each measure has four beats but each of those beats is constantly being subdivided into eighth-notes and sixteenth-notes, cluttering up each measure. This problem can be avoided by changing the way you write the beat.
Another reason for having different time signatures might be that it helps composers show which notes they think should be grouped together in the performance (this is called “phrasing”) – or it may simply look better to them!