A Common year is a calendar year with exactly 365 days, in contrast to the longer leap year. More generally, a common year is one without intercalation. The Gregorian calendar (like the earlier Julian calendar) employs both common years and leap years to adjust for differing astronomical measurements of the year: sidereal and tropical. In the Gregorian calendar, 303 of every 400 years are common years. By comparison, in the Julian calendar, 300 out of every 400 years are common years. In the Lunisolar calendar and the Lunar calendar, a common year consists of 354 days.