Tuplets · Music theory
Duplets, triplets, quadruplets, quintuplets and sextuplets: when a beat is divided another way.
What they are
Each beat of the measure has its normal division: in simple meters it divides into 2, 4 or 8 notes; in compound meters, into 3, 6 or 12. A tuplet puts a different number of notes into that same time.
It is marked with a number above the group, with a bracket if the notes are not joined by a beam. The group lasts as long as the notes it replaces; what changes is how long each one lasts.
Which note value each group uses
The general rule is to use the nearest normal division below. A quarter holds two eighths or four sixteenths; so a triplet is written in eighths, and a quintuplet, sextuplet and septuplet, in sixteenths.
When in doubt, the ratio is shown: 7:4 means seven in the place of four. Some composers write septuplets as 7:8, and modern notation has groups within groups. What matters is that the number and the values say unambiguously how long the group lasts.