Friday
the 13^{th} – Leap Year

Days to the 13th 
Sun 
Mon 
Tues 
Wed 
Thurs 
Fri 
Sat 
13Jan 
13 
6 
0 
1 
2 
3 
4 
5 
13Feb 
44 
2 
3 
4 
5 
6 
0 
1 
13Mar 
73 
3 
4 
5 
6 
0 
1 
2 
13Apr 
104 
6 
0 
1 
2 
3 
4 
5 
13May 
134 
1 
2 
3 
4 
5 
6 
0 
13Jun 
165 
4 
5 
6 
0 
1 
2 
3 
13Jul 
195 
6 
0 
1 
2 
3 
4 
5 
13Aug 
226 
2 
3 
4 
5 
6 
0 
1 
13Sep 
257 
5 
6 
0 
1 
2 
3 
4 
13Oct 
287 
0 
1 
2 
3 
4 
5 
6 
13Nov 
318 
3 
4 
5 
6 
0 
1 
2 
13Dec 
348 
5 
6 
0 
1 
2 
3 
4 
This table is for a year that is a leap year. This table shows the mod 7 value for the 13^{th}
of the month for each month. If it
occurs on a Friday the value will be 6, which corresponds to 6 mod 7. The day at the top of the table is the day on
which January 1 fell. We can see from
the table that each month has at least one Friday the 13^{th}. If January 1 falls on Sunday during a leap
year, there will be three months that the 13^{th} falls on Friday. During a leap year there will be no
consecutive months that have a Friday the 13^{th} since February now
has 29 days which is not an even multiple of 7.
Thus, the days in March will now fall on different days than those in
February, which is the only possibility for having consecutive days in a non
leap year. After a leap year the
starting day for the next year’s calendar will be the previous year’s starting
day plus 2. This table was also made on
Excel using the mod 7 formula.