In this series of videos I’ll be explaining what time signatures are and how they work.
In this video, Part 1, I’ll be:
Explaining the more common types of time signatures such as those listed here.
And I’ll be demonstrating how to calculate missing time signatures from a passage of music.
It’s really important that you understand note names and their values before looking at this video.
If you’re not sure of the names of notes have a look at my video ‘note names and their values’.
Firstly, it’s important to understand the meaning of a time signature.
So, here’s a time signature which most people have seen before: 4/4.  What does it tell us?
Well, the top number tells us how many beats are in a bar.  In this case there are 4 beats in the bar.
If the top number was 12 – there would be 12 beats in the bar.
If there was a 3, there would be three beats per bar and so on...
Technically you could have any number you like at the top (as long as it is a whole number and not a fraction like 2 and a half) but we’ll start with smaller numbers.
It’s the bottom number that seems to cause most confusion.
The bottom number tells us the 'type of beat'
By this, I mean, do we count in crotchets, minims, quavers or something else?
In this example the bottom number is 4. This effectively means,
which note (and here are a few)
can fit into a semibreve 4 times?
(4 times because there is a four at the bottom of the time signature).
The answer is a crotchet, this one,
as it has a value of 1 & can fit into a semibreve 4 times.
So we can say that the full meaning of 4/4 is:
4 crotchet beats per bar.
The four being the number of beats,
the crotchet being the type of beat.
Let’s look at another example. As there is an 8 at the bottom you need to work out which of these notes
can fit into a semibreve eight times.
Here’s our semibreve at the bottom of the screen.
A minim only fits twice
a semiquaver fits 16 times
whereas a quaver (which is worth half) fits 8 times into a semibreve
So, we’ve worked out that the 8 represents a quaver.
So the full explanation of this time signature is that there are
3 quaver beats in each bar.
The three being the number of beats,
the quaver being the type of beat.
This time signature, which has a two at the bottom, well that represents a minim.
As 2 minims (each worth 2) fit into a semibreve.
which has a value of 4.
So the full explanation of this time signature is
3 minim beats per bar.
Hopefully by now you’re getting the hang of what time signatures represent.
So let’s look at some fairly common time signatures:
4/4. This is a very common time signature.
So much so it is often abbreviated to this symbol.
The C is short for ‘Common Time’.
Now, I’ve already said that this time signature means there are 4 crotchets beats in a bar.
This is true but it clearly doesn’t mean that we can only write 4 crotchets in each bar,
of course not!
We can write anything we wish in the bar as long as the total value of the beats is exactly 4,
no more and no less.
So, this is acceptable,
so is this. The four semiquavers equal beat 1,
this crotchet is beat 2,
The two quavers equal one beat
and the final crotchet equals one beat
so there are four beats in this bar
This bar is also acceptable:
the four quavers equal two,
the final minim also equals two.
2+2 equals the 4 beats we are allowed in this bar.
The same is true for every other time signature.
No matter what the time signature is displayed every bar *must* equal the number of beats in the bar.
So, here’s 3/8. Remember, this means three quaver beats in each bar.
it doesn’t mean you can only have 3 quavers in each bar,
you could have 6 semiquavers if you wanted.
Or, indeed, almost any type of beat as long as it doesn’t exceed 3 quavers.
I mentioned a few moments ago that this symbol, means 4/4.
Here’s a time signature that looks very similar but means something else.
Notice that there is a line through the middle as if the C has been cut in two.
Well, it is often called cut-common time and represents 2/2.
So, firstly, remember:  this is common time and equals 4/4.
This is cut-time (or cut common time) and represents 2/2.
Now, a lot of students ask me why have 2/2 when you can just have 4/4
as they both have four crotchet beats in them.
My answer is simply – “no”
Although 4/4 has four crotchet beats, 2/2 does not; it has 2 minim beats.
Okay, 2 minims can be split into 2 crotchet beats each.
So you may ask why have 2/2 at all?
Well, there are a few reasons for this but the most common reason is to do with the tempo
or pulse of the music.
For example, 2/2 is quite commonly used for faster music.
4/4 is generally used for slower (not slow) slower music in 4.
Don’t worry about this too much. If you’re writing a piece of music it doesn’t really matter whether you were to use 2/2 or 4/4.
What’s important is that you understand that 4/4 has 4 crotchet beats per bar
and 2/2 has 2 minim beats per bar.
This does cause a problem if you’re sitting a music theory exam
and asked what the time signature could be
for this piece of music.
without knowing how fast the music is to be played
it’s pretty impossible to know for certain.
Therefore, the answer could be 4/4 or 2/2,
you’d get a mark for either.
The same dilemma appears in many other time signatures, such as 3/4 or 3/8.
Perhaps you want to compose a piece of music in 3 but you're not sure whether to use 3/4 or 3/8.
They both have 3 beats (3/4 is in crotchet beats whereas 3/8 in quaver beats).
Generally, 3/8 is used for faster rhythms but there is no real hard and fast rule,
so don’t worry too much about this.
I’ll look at this a little more in my videos about composition.
Now, before we tackle some exam questions, there’s something very important I need to point out here.
Here’s a full bar of quavers in 2/4...
and 3/8.
Notice how in 2/4 the quavers are in groups of 2,
whereas in 3/8 they are in a group of 3.
I talk about the grouping of notes in my video about beaming, but as a rule of thumb, for the moment...
quavers in a time signature with an 8 at the bottom
are grouped together in 3’s.
Do remember this!
Okay, if you’re going to be sitting a music theory exam you often come across questions whereby you’ll be given a melody (or rhythm)
and you have to write down what the time signature is.  Let’s try a few examples:
Now, the first thing to notice is that the quavers are grouped in 2’s.
This immediately means we can ignore any time signature with an 8 at the bottom.
If there were a 2 at the bottom of the time signature we’d be counting in minims as the 2 represents minim beats.
Now, if we add all the note values together, half+half+1 = 2.
1 minim equals 2 therefore as there is one minim in this bar, the top number in our time signature, would be 1
making the full time signature 1/2.
This is a very rare time signature and, if I think about it, I don’t think I’ve ever played a piece of music in 1/2.
So, let’s try again – let try counting in crotchets,
so a four at the bottom.
the two quavers, each worth half, equal one crotchet, and there’s another crotchet here – so there are 2 crotchets in this bar.
As there are 2, we add a two to the top of our time signature.
So 2/4, which is a much more common time signature, is the answer.
How about this one?
There’s no quavers in this one so we can’t dismiss time signatures with an 8 at the bottom just yet, so let’s look at the options.
If there was an eight at the bottom (meaning quaver beats) we have to count up all of the quavers in the bar:
In this first minim, there are four quavers (remember that each quaver equals half)
The second minim therefore has another four quavers.
This crotchet is made up of two quavers
As is this one.
And here’s another minim – so another 4 quavers.
If we count up all of the quavers there is a total of 16, so our time signature could be 16/8.
I’ll pop this at the bottom of the screen as a possible answer.
Okay, so how about if we count in crotchets – a 4 at the bottom of the time signature.
2 crotchets here,
2 here,
1
and 1
and another 2.
We count up all the crotchets...
there are 8 of them so the time signature could be 8/4
I’ll pop this at the bottom of the screen as well.
Finally, how about counting in minims?
A two at the bottom of the time signature.
1 minim here,
another 1 minim here,
these two crotchets equal 1 minim
and 1 final minim.
So 4 minims in total, this could be 4/2.
So, which of these options to choose?
Well, the answer is 4/2.
now there are lots of reasons for this
some which are quite complex and I’ll discuss further in part 3,
but the main feel or pulse of the beat is clearly in 2 due to the abundance of minims.
It’s also easier to count to four rather than having to count to 8 (as in 8/4) in every bar.
Besides, why write 8/4 when, like fractions, it’s easier to express as 4/2?
As for 16/8, well – this is actually a very rare time signature.
If you’re studying music theory with the associated board you’ll never get asked a question about 16/8 – it’s what’s called an irregular time signature
and I’ll be looking at these in part 4 of this series of videos.
In a nutshell – irregular time signatures are when the beat cannot be split equally into twos or three’s.
Remember I said that when the time signature has an 8 at the bottom, the quavers are grouped into three’s.
Well, you can’t group 16 quavers into equal groups of three’s,
there’d have to be two groups of two.
This makes it an irregular time signature.
4/2, however, is a very common time signature and emphasises the minim beats.
Quite a tricky questions this one.
In this example there are two bars and the second bar has a rest in it.
Always make sure that you count any rests in a bar when calculating a time signature,
rests are just as important as the notes.
To calculate the time signature – let’s start with counting in crotchets,
a four at the bottom of the time signature.
This wouldn’t work as we’d end up with 1 and half in each bar.
Remember, you can only have whole numbers at the top number of a time signature.
It can’t be a minim beat as there isn’t even 1 minim in each bar.
But we can count in quavers, an 8 at the bottom of our time signature.
2 quavers in a crotchet,
and one here;
so there are 3 quavers in this bar.
Let’s just check the 2nd bar.
There are 3 quavers (don’t forget to include that quaver rest).
We’ve already put the 8 at the bottom of the time signature to represent the quaver beats.
We’ve calculated that there are 3 quaver beats per bar so we can add in the 3 as the top number to our time signature.
So, the answer; is 3/8.
One final example:
No quavers in this question but if we did count them – there are 8 so it could be 8/8.
If we counted crotchets, there are four so the answer could be 4/4.
If we counted minims, there are two so the answer could be 2/2.
It’s not 8/8 as why have 8/8 when you can have 4/4?
a simpler way to express 8 quavers in a bar?
Remember, with an 8 at the bottom, we're looking to group our quavers in groups of 3s.
In 8/8, it's not possible to group all of your quavers, equally, into groups of 3s. There'd have to be groups of twos.
So it makes it a somewhat irregular time signature.
So, is it 2/2 or 4/4?  Well, it could be either – you’d get a mark if you put 4/4 or 2/2.
In fact, you’d also get a mark if you chose to use the symbols for Common Time or Cut Common-Time.
There is simply no way we can tell whether the composer wrote this in 4/4 or 2/2.
So just be aware that sometimes, and only sometimes, there may be a choice of answers.
Now I could keep providing examples like those we’ve just tackled but as there is an unlimited amount of possibilities I’ll leave it there.
The key thing to do is to count and explore  each time signature option.  In time you’ll get quick at this and be able to spot missing time signatures very quickly.
In the next video I’ll be explaining the difference between simple and compound time signatures.  In the meantime, thanks for watching.
Subtitles: MusicTheoryGuy, October 2015
