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How is it possible that a 4/4 signature corresponds to a 12/8 signature ? 4/4 is equal to 1 and 12/8 is more than 1 .

If i try to divide a 1/4 in 3 notes i get 1/12, not 1/8 as the 12/8 should be.

  • This could well be a duplicate question. – Tim Sep 22 '18 at 13:56
  • Possible duplicate of What feel is 12/8 meter and why? – guidot Sep 22 '18 at 16:24
  • I don't know about that being a duplicate of this question, that asks about "feel" of 12/8. Possibly a duplicate of something else? – user45266 Sep 23 '18 at 17:11
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The time signature does not function as a fraction in mathematics. The top number serves to tell how many beats per measure, while the bottom number tells what rhythm gets counted as one beat. In 4/4, for instance, the top 4 states that there are four beats per measure, whereas the bottom 4 states that one quarter note equals one beat. Therefore, with 4/4, you'll feel a definite "one two three four, one two three four" throughout the song.

In 12/8, you'll have 12 eighth notes per measure. However, rather than feeling "1 2 3 4 5 6 7 8 9 10 11 12," you'll normally feel the eighth notes in groups of three -- "1 2 3 4 5 6 7 8 9 10 11 12". Or, to simplify, "one and a two and a three and a four and a".

This is called subdivision of the beat, this grouping of eighth notes into groups of either two or three. In 4/8, for instance, you'll feel eighth notes in groups of two (1 2 3 4), whereas in 6/8, 9/8, or 12/8, you'll feel the eighth notes grouped into groups of three.

Hope this helps!

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They are related in the sense that they are both quadruple time, meaning in both instances there are four beats to a bar. 4/4 time is just Simple Quadruple time where a beat is equal to a crotchet and 12/8 is Compound Quadruple time where there are four beats of dotted crotchets.

In essence, simple time means beats without dots and compound time means beats with dots. They are both four-time the one just having regular crotchet beats and the other dotted crotchet beats.

  • Does this mean that one bar in 12/8 time is half as long again as one bar in 4/4? – Tim Sep 23 '18 at 7:18
  • @Tim 12/8 is 1.5 times as long. – Neil Meyer Feb 28 at 7:54
  • That could be true. How long is a crotchet? Quite often something meant to be played in swing feel will be notated in 4/4, for simplicity, and a little picture at the top shows a crotchet = 3 triplet quavers. At this point, 4/4 equals 12/8 in length. – Tim Feb 28 at 8:56
  • 6 crotchets vs 4 crotchets = 1.5 times as long. – Neil Meyer Feb 28 at 9:01
  • 4 crotchet = 12 quaver triplets. But all of this, without bpm, is meaningless. One minim @ crotchet =120bpm is the same length as one crotchet @crotchet = 60 bpm. Not many pieces will be written part in 4/4, rest in 12/8. Semantics. – Tim Feb 28 at 9:07
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4/4 is four quarter notes to the bar. 12/8 is four dotted quarters to the bar. Useful for music where the sub-divisions of each beat are mostly into three. Saves you writing a load of triplets (those groups of three 8th notes with a 3 bracket over the top, indicating that the three are to fit into the space normally taken by two of them).

Simple time. One-and-Two-and-Three-and-Four-and. 4/4. Or One-and-Two-and One-and-Two-and. 2/4. (Etc. That's not an exclusive list of Simple time signatures.)

Compound time. One-and-a-Two-and-a-Three-and-a-Four-and-a/ 12/8. Or One-and-a-Two-and-a One-and-a-Two-and-a. 6/8. Etc.

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Whilst the time signature looks like a mathematical fraction, in a way it is, but there again, it isn't !

The top number, just like a fraction, tells how many there are, the bottom tells what they are. So, in 4/4, there are 4 of them (top), and the bottom tells they are crotchets, aka quarter beat note value, in each bar or measure. So far so good. Just like a fraction.

When we get to a time signature like 6/8, there are 6 quavers (eighth notes) in each bar. The confusing part here is that they are arranged in two lots of three. So the count is either 1--2-- or put in another way, 123456. Still with this 'fraction' - 3/4 time has the same number of 'bits' in each bar, but they get emphasised differently. 123, as there are 3 crotchets to count.

Now on to 12/8. It's pretty well double 6/8 (surprise!), but counted 1--2--3--4-- in each bar. But - those quavers can be seen in a timing manner that 3 get played in the time of two in 4/4 time sig. So, in 4/4, using normal eighth notes, there will be 8, counted 1&2&3&4& in each bar, but the equivalent timing at the same tempo for 12/8 will be 1&a2&a3&a4&a. So both can be equal in timing (bpm) but their time sigs won't be equal mathematically. It ain't easy!

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