Most people have probably thought at one time or another, why isn't 4/4 time the same as say 8/8 time or 2/2 time? (Anyone who knows about reducing fractions can attest to that).

I think time signatures really are anachronistic. Really you just want to know is there 3 beats, 4 beats or even 5 beats in a bar.

Mostly the only ones used are 3/4, 4/4 and very rarely 5/4.

So is it just convention to use this method. Or is there some hidden meaning. I mean a semibreve is always 4 crotchets no matter what the time signature is.

So is this just an anachronism we have to put up with or does anyone find this weird way of expressing the beats in a bar useful?

  • 3
    For the record, 2/2, 4/4, and 8/8 are very different in terms of beats and accentuated beats! Just the top number matters in this case: 2/2 means two beats, first accentuated, 4/4 means 4 beats, etc. Accent always on the first beat. The question should rather be: why 4/2 vs. 4/4 vs. 4/8, for example (with appropriate tempos, they are all equivalent).
    – Noldorin
    Commented Nov 18, 2019 at 17:20
  • 1
    Compare six eighth's notes in 3/4 time ( ONE and, two and, three and, …) with 6/8 time (ONE two three, Four five six). They sound completely different. Commented Nov 19, 2019 at 0:29
  • A time signature isn't a fraction. For instance, the 3 over 4 time signature is not the same as 6 over 8 Commented Nov 20, 2019 at 13:02

6 Answers 6


If you think the denominators are arbitrary, try notating a stately sarabande in 3/8 time - you'll drown in beams and flags. Next, try notating a lively tarantella in 3/1 time - you'll be overwhelmed by ties and similar-looking note heads and be unable to read anything.

The point of having different-length notes available rather than just clarifying everything with tempo indications is that the choice of base beat is a rough tempo indication. It's easier to assimilate this information by consuming the familiar shape of quavers, crotchets etc. than to keep remembering "oh yeah, this is supposed to be really fast, like, 192 BPM". Gestalt recognition is a thing, and it's a good idea to take advantage of it.

The standard musical notation system is actually pretty well adjusted to the quirks of human perception. It has a couple of longstanding bugs in it (for instance, the inability to distinguish half-tone and whole-tone intervals at a glance), but time signatures aren't one of them.

  • I've read that, back in Baroque times, slow music was actually associated with shorter note values and fast music with longer note values. According to that source, Telemann's Gulliver Suite was pushing that to extremes with its Lilliputian Chaconne (in 3/32 time) and Brobdingnagian Gigue (in 24/1 time), but it wasn't as extreme as you might think.
    – Dekkadeci
    Commented Nov 18, 2019 at 11:40
  • @Dekkadeci - yes, part of the thinking is that: shorter note values for slow music will take up less paper, so you can fit more on a page. Fast music uses larger values which are easier to read and will better convey the urgency required. Commented Nov 18, 2019 at 13:15
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    @Dekkadeci - Not sure if it's what you're referring to, but over the years there's been a sort of ‘note inflation’: the length of time represented by a given note has steadily increased. (In some of the earliest notation, the two main note values were a ‘lunga’ (long) and a ‘breve’ (brief; ½ or ⅓ of a lunga). The lunga hasn't really survived, but you might still see a breve occasionally: in US terminology it's two whole notes, or 2 bars of 4/4.) It probably results from centuries of composers wanting their music to go faster than performers can manage :-)
    – gidds
    Commented Nov 18, 2019 at 17:32
  • My point wasn't that denominators are arbitray but that in most cases you can just use 4 as int 3/4 4/4 5/4. My point was as fractions 2/4=3/6=4/8 etc.
    – zooby
    Commented Nov 18, 2019 at 18:27
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    @gidds the longa (note spelling) is still seen in some modern editions of Renaissance music. That the breve is twice as long as a whole note explains why whole notes are known in some parts of the world as semibreves.
    – phoog
    Commented Nov 18, 2019 at 18:28

In some pieces the beat is divided into 2, and the half-beats might in turn be halves. In that case, you might well choose to notate it with the crotchet/quarter-note as the beat, thus 2/4, 3/4 or 4/4, say.

But in other pieces, the beat is divided into 3. In these pieces it might be better, for the sake of those notes of one-third of a beat, to notate it with the dotted crotchet/quarter-note as the beat, thus 6/8, 9/8 or 12/8, say.


If you play alone you might ignore 2/2 and 4/4 - as the accents will be similar, but if you play with others in an ensemble or orchestra this differentiation will be more important: mind that in 2/2 you count to 2 while in 4/4 you count to 4, and if you have even a conductor he will conduct only 1-2 in a 2/2 time. So it's important for orientation, telling where we are, from where we start, even if the rhythm feeling might not differ so much as we think.

Yes, they make sense! Also consider the examples of the other answers.

  • I can see why that might be important when you have a conductor and he is marking out the beats. But, when playing alone it does seem kind of pointless. Then again when you have a conductor, he or she can communicate to the orchestra how they are marking the beats so it leaves the time signature irrelevent.
    – zooby
    Commented Nov 18, 2019 at 18:22

In time signatures, the top number refers to the number of beats per bar, while the bottom number refers to the note value of the beat. Unlike fractions, 3/8, 3/4 and 3/2 all have the same number of beats per bar. The values are different so as to be convenient to read or write in different tempos. All time signatures have specific meanings and uses. 6/8, for instance, is also often used and only has 2 beats per bar, divided into three quavers each.

  • My point is 3 beats in a bar is the same as 6 beats in a bar payed twice the speed.
    – zooby
    Commented Nov 18, 2019 at 18:24
  • 1
    @zooby but it isn't: a six-beat time signature is invariably used to specify two beats subdivided in three, while a three-beat time signature is used to specify three beats subdivided in two.
    – phoog
    Commented Nov 18, 2019 at 18:29
  • Well the beats are all in your head anyway. Unless there is a conductor or a metronome.
    – zooby
    Commented Nov 18, 2019 at 18:30
  • 5
    @zooby no they're not. Or rather, it's not just about the beats but about accent, stress, and grouping. Consider setting the following seven-syllable phrases as a measure of six eighth notes followed by a dotted half note: "would you like to hear me sing?" is 3/4, while "wouldn't you rather go home?" is in 6/8.
    – phoog
    Commented Nov 18, 2019 at 18:33
  • 1
    @zooby a good violinist, or actually any violinist who is at least passably mediocre, will play those two phreases differently, even if they both comprise the same notes (for example C-D-E-F-E-D-C).
    – phoog
    Commented Nov 18, 2019 at 18:47

I feel the difference is most pronounced with 6/8 vs 3/4. Consider a measure with six 8th-notes. In 6/8 time the emphasis will be on the first and fourth note, but in 3/4 time it will be on the first, third and fifth note.

I've come up with a small example. You can listen to it here: https://musescore.com/user/16549076/scores/5852825 The original melody is in 6/8 or even 12/8 (I can't remember), and it sounds completely different with the 3/4 emphasis. Note that Musescore automatically grouped the notes just right to help the player get the emphasis right.

Which measures have which notes emphasized is a matter of tradition. Using the measure that fits what you want makes it easy for experienced musicians to play the piece the way the composer intended.

  • 1
    My favourite illustration of this (although not worth a separate answer) is 'America' from West Side Story. The bars of the main theme alternate 6/8 and 3/4 with very clear distinction between two beats and three beats. I believe the original score was notated as 6/8+3/4 at the start. youtu.be/_e2igZexpMs?t=59
    – dbmag9
    Commented Nov 18, 2019 at 21:45

Some of it is historical convention.

Before the metronome longer note values in the lower number of the time signature implied slow tempos.

While 3/4 and 3/2 as fractions kind of reduce mathematically to the same thing, it isn't important musically. 3/2 in the past meant play at a slow tempo.

Another important thing to be aware of is simple meter versus compound meter like 3/4 versus 6/8. As fractions they reduce to the same thing, but musically the metrical pulse is different. As you pointed out knowing if the rhythm is grouped by 2 or 3 (duple or triple) is essential. 3/4 is triple with three strong pulses, but 6/8 is compound and has two strong pulses. Reducing 6/8 to 3/4 is a mistaken reading of time signatures and looses the important information about where the metrical pulse is.

...Anyone who knows about reducing fractions

Time signatures are not fractions, they are time signatures.

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