This calendar is about the size of a large postage stamp.
The first column contains numbers for the months of the year. The middle gives the weekday on which the first falls. The last column gives the date of the first Sunday of that month. With this data, you can easily figure out the rest of the dates that you need to know.
The first line is interpreted: January and April and July start on a Tuesday and their first Sunday falls on the 6th — so you know that the other Sundays are 13, 20, 27. Once you know the Sundays, you can get to the Mondays by adding 1, Tuesdays by adding 2, and so on.
Only the last column is actually needed for figuring out the other dates; the middle column is given because people frequently want to know quickly what day of the week the first falls on.
Computing dates takes only a little practice. If you need to know what day of the week the 24th of January falls on, you learn to break 24 down into three sevens plus three. The first is a Tuesday, so 1 plus 21 is a Tuesday. If the 22d is a Tuesday, the 24th must be a Thursday.
Or: you know immediately from the last column that the 20th must be a Sunday (from the sequence 6, 13, 20, 27). Twenty plus four must be the same as Sunday plus four days, which is a Thursday.
If this version is still too minimalist for your taste, you might prefer the "unreduced" format below.