Calendar year

Quarter year

The calendar year can be divided into four quarters, often abbreviated as Q1, Q2, Q3, and Q4. Since they are three months each, they are also called trimesters. In the Gregorian calendar:

1. First quarter, Q1: January – March (90 days or 91 days in leap years)
2. Second quarter, Q2: April – June (91 days)
3. Third quarter, Q3: July – September (92 days)
4. Fourth quarter, Q4: October – December (92 days)

In some domains, weeks are preferred over months for scheduling and reporting, so they use quarters of exactly 13 weeks each, often following ISO week date conventions. One in five to six years has a 53rd week which is usually appended to the last quarter. It is then 98 days instead of 91 days long, which complicates comparisons.

In the Chinese calendar, the quarters are traditionally associated with the 4 seasons of the year:

1. Spring: 1st to 3rd month
2. Summer: 4th to 6th month
3. Autumn: 7th to 9th month
4. Winter: 10th to 12th month

See also

References