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Reading rhythm, part 12: time signatures

A time signature is the 2 numbers on top of each other at the start of a piece:

time signature

Almost all popular music is written in 4/4 (i.e. it has the time signature 4/4), so if you’re playing genres like pop, rock, hip hop, country, R’n’B, etc., you don’t really have to think about time signatures since they’re almost always the same. However, if you’re playing genres like classical, jazz, folk, alternative, etc. not everything will be in 4/4. You might have noticed that pieces in my Intermediate Classical course use a variety of time signatures, like 4/2, 3/4, and 12/8.

What do they mean?

The top number in a time signature

We already mentioned a few things about time signatures that might have allowed you to guess how they work:

  • Beethoven’s “Ode to Joy” had 4 beats in a bar and had the time signature 4/4.
  • Brahms’s Lullaby had 3 beats in a bar and had the time signature 3/4.

So you might have correctly guessed that:

  • the top number in a time signature (usually*) tells you how many beats there are in a bar

The bottom number in a time signature

The second part is less obvious. My note length chart also said that a 14-note is 1 beat if the bottom number of the time signature is 4:

1/4-notes

What if the bottom number’s 2? Then a 12-note is 1 beat. And if it’s an 8? Then an 18-note is 1 beat:

  • the bottom number in a time signature (usually*) tells you what we’re counting as a beat

Let’s work through a couple of examples where the bottom number is something other than a 4, so you get used to counting something other than a 14-note as 1 beat.

Counting 12– or 18-notes as beats

So:

  • in the time signature 4/2 there are 4 × 12-notes in a bar
  • in the time signature 6/4 there are 6 × 14-notes in a bar
  • in the time signature 3/8 there are 3 × 18-notes in a bar

Music teachers often say not to think of time signatures like fractions, and it’s true that technically speaking they’re not, but they do multiply like fractions:

  • 4/2 = 4 × 12-notes
  • 6/4 = 6 × 14-notes
  • 3/8 = 3 × 18-notes

The exceptions

Okay, so why the “usually” in the above 2 rules? Here are the exceptions:

  • *unless the top number is 6, 9, or 12, then there are 2, 3, or 4 beats in a bar, and each beat is split into 3

What?

“Compound” time signatures

Let’s look at my arrangement of Chopin’s Nocturne Op. 9 No. 2. The time signature is 12/8. Does that mean we count each bar:

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12?

No. Look at the LH:

Chopin Nocturne

The 12 × 18-notes are grouped into 4 groups of 3. And that’s how you count 12/8:

1, 2, 3, 2, 2, 3, 3, 2, 3, 4, 2, 3

As 4 beats, where each beat is split into 3.

Chopin Nocturne with beats

How about 6/8? We can look at Puccini’s “O mio babbino caro” for guidance:

"O mio babbino"

The 6 × 18-notes are split into 2 groups of 3.

"O mio babbino" with beats

Let’s see how that works in practice:

So if the top number of a key signature is 6, 9, or 12, there are 2, 3, or 4 beats in a bar, and each beat is split into 3:

  • top number is 6 → 2 beats split into 3
  • top number is 9 → 3 beats split into 3
  • top number is 12 → 4 beats split into 3

Note: this applies to all multiples of 3 apart from 3: if the top number is a 3 each bar isn’t “1 beat split into 3”, it’s just 3 beats, e.g. Beethoven’s “Für Elise” in the 1st video on this page.

3/4 versus 6/8

A good way of understanding compound time signatures is to compare the time signatures 3/4 and 6/8. They both have 6 × 18-notes in a bar, but:

  • in 3/4 they’re split into 3 groups of 2
  • in 6/8 they’re split into 2 groups of 3

Compare Brahms’s Lullaby (3 beats split into 2):

Brahms's Lullaby with beats

with Puccini’s “O mio babbino caro” (2 beats split into 3):

"O mio babbino" with beats

Leonard Bernstein’s “America” from West Side Story cleverly switches between the two patterns every couple of bars:

Bernstein's "America"

5/4, 7/8, and other uncommon time signatures

There are some pieces with some number other than 2, 3 or 4 beats in a bar, e.g. “Take Five” and the theme from Mission Impossible, which are both in 5/4, or Dave Brubeck’s “Unsquare Dance”, which is in 7/8. However they’re notable precisely because they’re so unusual – don’t worry about unusual time signatures until you encounter them, which might be never.

Where to go from here

Now that you’ve completed my 3 sight reading courses, go and learn some pieces from my Intermediate Classical course or some of my popular arrangements. Or, if you haven’t done them yet, work through my Read Music Fast! and Read Music Fast! Part 2 courses.