Time signatures, from simple to irregular

The Grade 5 exam

Grade 5 theory is an online exam in seven sections, marked out of 75. This course takes the sections in order, one unit each, and ends with a full mock paper:

Section 3, keys and scales, carries the most marks. Every other section is worth the same, so no part of the course is a side road.

What a time signature tells you

A time signature is two numbers at the start of the music.

• The top number tells you how many.
• The bottom number tells you which note value: 2 a minim, 4 a crotchet, 8 a quaver, 16 a semiquaver.

So 3/4 means three crotchets in every bar, and 3/8 means three quavers. That is the whole meaning of the numbers. Whether those notes are the beats depends on the kind of time.

Simple time

In simple time each beat is a plain (undotted) note, and it divides into two halves. The top number is the number of beats:

• 2 beats: duple time
• 3 beats: triple time
• 4 beats: quadruple time

So 3/2 is simple triple: three minim beats.

Compound time

In compound time each beat is a dotted note, and it divides into three. You can spot it because the top number is 6, 9 or 12. Divide the top number by 3 to find the beats:

• 6/8 has six quavers, grouped in threes: two dotted crotchet beats, compound duple.
• 9/8 has three dotted crotchet beats: compound triple.
• 12/8 has four: compound quadruple.

The same works with other bottom numbers: 6/4 has two dotted minim beats, 9/16 three dotted quaver beats, 12/16 four dotted quaver beats.

Tip: 3/8 is simple triple (three quaver beats), not compound. Compound time needs at least two groups of three, so the top number is 6, 9 or 12.

Irregular time: 5 and 7

Grade 5 adds irregular time signatures: 5/4, 7/4, 5/8 and 7/8. Five or seven cannot be shared into equal beats of two or three, so each bar mixes groups of 2 and 3.

• 5/8 groups as 3 + 2 or 2 + 3.
• 7/8 groups as 2 + 2 + 3, 3 + 2 + 2 or 2 + 3 + 2.

The beams show you the groups: each beamed group (or longer note) is one group.

Worked example: which time signature fits?

When the time signature is missing, add up one bar, then find the signature that holds exactly that much.

1. Count in crotchets: a dotted crotchet 1.5, a quaver 0.5, then three crotchets 3. Total 5 crotchets.
2. The beams and long notes show crotchet beats, not dotted ones.
3. Five crotchet beats: 5/4.

Tip: two time signatures can hold the same amount (6/8 and 3/4 both hold six quavers). The grouping decides: 6/8 shows two groups of three quavers, 3/4 shows three pairs.

Upbeats, recapped

A melody may start with an upbeat: a short first bar before the first strong beat. The last bar is short by the same amount, so the upbeat and the last bar together make one full bar.