Editing Leap year starting on Thursday (section)

=== Gregorian Calendar ===
Leap years that begin on Thursday, along with those [[Leap year starting on Monday|starting on Monday]] and [[Leap year starting on Saturday|Saturday]], occur least frequently: 13 out of 97 (≈ 13.402%) total leap years in a 400-year cycle of the [[Gregorian calendar]]. Their overall occurrence is thus 3.25% (13 out of 400).

For this kind of year, the corresponding [[ISO week date|ISO year]] has 53 weeks, and the ISO week 10 (which begins March 1) and all subsequent ISO weeks occur earlier than in all other years, and exactly one week earlier than [[Common year starting on Friday|common years starting on Friday]], for example, June 20 falls on week 24 in common years starting on Friday, but on week 25 in leap years starting on Thursday, despite falling on Sunday in both types of year. That means that moveable holidays may occur one calendar week later than otherwise possible, e.g. Gregorian [[Easter]] Sunday in week 17 in years when it falls on April 25 and which are also leap years, falling on week 16 in common years.{{#tag:ref|Leap years when Easter Sunday falls on April 25 are only possible years when Easter Sunday can fall on week 17.}}

{| class="wikitable"
|+ Gregorian leap years starting on Thursday<ref name=math/>
!scope=row| Decade
! 1st !! 2nd !! 3rd !! 4th !! 5th !! 6th !! 7th !! 8th !! 9th !! 10th
|-

! style="background-color:#efefef;" | [[17th century]]
| [[1604]] || || || [[1632]] || || [[1660]] || || || [[1688]] || 
|-
! style="background-color:#efefef;" | [[18th century]]
| || || [[1728]] || || || [[1756]] || || || [[1784]] || 
|-
! style="background-color:#efefef;" | [[19th century]]
| || || [[1824]] || || || [[1852]] || || [[1880]] || || 
|-
! style="background-color:#efefef;" | [[20th century]]
| || [[1920]] || || || [[1948]] || || || [[1976]] || || 
|-
! style="background-color:#efefef;" | [[21st century]]
| [[2004]] || || || [[2032]] || || [[2060]] || || || [[2088]] || 
|-
! style="background-color:#efefef;" | [[22nd century]]
| || || [[2128]] || || || [[2156]] || || || [[2184]] ||
|-
! style="background-color:#efefef;" | [[23rd century]]
| || || [[2224]] || || || [[2252]] || || [[2280]] || || 
|-
! style="background-color:#efefef;" | [[24th century]]
| || [[2320]] || || || [[2348]] || || || [[2376]] || || 
|-
! style="background-color:#efefef;" | [[25th century]]
| [[2404]] || || || [[2432]] || || [[2460]] || || || [[2488]] || 
|-
! style="background-color:#efefef;" | [[26th century]]
| || || 2528 || || || 2556 || || || 2584 ||
|-
! style="background-color:#efefef;" | [[27th century]]
| || || 2624|| || || 2652 || || 2680 || ||
|}

{| class="wikitable"
|+ 400-year cycle
|-
! 0–99
| 4 || 32 || 60 || 88
|-
! 100–199
| 128 || 156 || 184 ||
|-
! 200–299
| 224 || 252 || 280 ||
|-
! 300–399
| 320 || 348 || 376 ||
|}