| Name |
Symbol |
Value |
Description/Notes |
| century |
c |
100 years |
|
| decade |
|
10 years |
|
| fortnight |
|
14 days;
2 weeks |
|
| generation |
|
25-30 years |
Generally accepted range |
| julian year |
|
365¼ days |
|
| leap year |
|
366 days |
Leap years are those exactly divisible by 4 except century years, which are only leap years if exactly divisible by 400
|
| lunar month |
|
28 days;
4 weeks |
Formerly used in some legal contracts, thus a 12-month contract was actually in force for 48 weeks
|
| millennium |
|
1,000 years |
|
| olympiad |
|
4 year cycle |
|
| quarter |
Q |
3 calendar months |
Quarters begin in January, April, July and October |
| |
|
30.4369 |
Average number of days in a calendar month, calculated from year 2000 to 2999 inclusive
|
