3/4 vs 6/8 Time Signature: What's the Difference?

Reading a time signature

A time signature has two numbers. The top number tells you how many notes fill a bar; the bottom number tells you which kind of note. A 4 on the bottom means quarter notes, an 8 means eighth notes.

3/4 means three quarter notes per bar.
6/8 means six eighth notes per bar.

Since one quarter note equals two eighth notes, both bars hold exactly six eighth notes. On paper they’re the same length. They sound different because the beat is divided differently, and that’s the whole story of 3/4 vs 6/8.

Simple meter: 3/4

In 3/4 there are three beats per bar, and each beat splits into two eighth notes. The six eighths fall into three pairs, counted “1 & 2 & 3 &.”

A meter whose beats divide into two is called a simple meter. With three beats per bar, 3/4 is simple triple.

Compound meter: 6/8

In 6/8 the six eighth notes fall into two groups of three. That gives you two big beats per bar, and each big beat is a dotted quarter note long. Counted in eighths, the weight lands on 1 and 4: “1 2 3 4 5 6.”

A meter whose beats divide into three is called a compound meter. With two big beats per bar, 6/8 is compound duple. A handy rule of thumb: a top number of 2, 3 or 4 usually means simple meter, while 6, 9 or 12 usually means compound.

Here’s the part that trips people up: in compound meter, the bottom number doesn’t name the beat. It names the division of the beat. The real beat in 6/8 is the dotted quarter, not the eighth note.

Hear the difference on a metronome

Reading about it only goes so far; hearing it makes it click. In our metronome, the BPM always counts the note on the bottom of the time signature, so in 6/8 each click is one eighth note.

3/4 gives you three beat blocks with the default accents strong, weak, weak.
6/8 gives you six beat blocks with the default accents strong, weak, weak, medium, weak, weak. The medium accent on beat four is what makes the 3+3 grouping audible.

To compare them fairly, make the bars the same length: set 6/8 to 120 BPM and 3/4 to 60 BPM. Both bars now last three seconds. Then turn on the 8ths subdivision in 3/4 so it also clicks six times per bar. The number of clicks is identical; only the emphasis moves. In 3/4 the main beats land on clicks 1, 3 and 5. In 6/8 they land on 1 and 4.

You can also tap the beat blocks to change the accents yourself. Make beat four strong in 6/8 and the two-beat feel gets even clearer. Or accent beats 1, 3 and 5 instead, and the very same six clicks start to sound like three beats.

Counting 6/8 in 6 or in 2

How you count 6/8 depends on the tempo.

In 6. At slow tempos, count every eighth note, “1 2 3 4 5 6,” with the metronome clicking each one.
In 2. At faster tempos, counting six becomes a blur. Count just the two big beats, “1 2,” and feel the three eighths inside each.

To practice counting in 2, set the metronome to 2/4 and turn on the Triplets subdivision. Each beat click is now a big beat, with two softer clicks inside, which is the 3+3 feel exactly. Because the beat is now the dotted quarter, set the BPM to one third of your 6/8 tempo: 6/8 at 120 becomes 40 BPM.

Waltz feel vs jig feel

3/4: The waltz is the classic example. One dance step per bar, with an “OOM-pah-pah” feel.
6/8: The jig is the classic example. Two big, rolling beats per bar.

Switching between them

The best way to make the difference physical is to alternate between the two at the same speed:

Set the metronome to 6/8 at 120 BPM and clap six eighth notes per bar, leaning a little on 1 and 4.
After four bars, switch to 3/4 at 60 BPM with the 8ths subdivision on. Keep clapping six per bar, but now lean on 1, 3 and 5.
Repeat a few times. The number of claps never changes; only where the weight falls does.

When you meet a new piece and aren’t sure how it should feel, check the time signature, set the metronome’s accents to match, and play a few bars. The grouping that sits naturally under your playing is the meter you’re hearing.