Unfortunately, it seems to be impracticably complex to devise a true lunar month calendar in which each month averages 29.5 days (the amount of time it takes the moon to orbit the earth). In such a system every month would alternate between having 29 and 30 days. The main problems are that there is no clean and simple way to include 12.37 of these lunar months into one 365 day year while maintaining the consistency of season start dates and the simple predictability of constant month lengths. The World Calendar is another attempt at calendar simplification by having the first month of each quarter of the year contain 31 days and always begin on a Sunday and all successive months containing 30 days, respectively beginning on Wednesdays and Fridays. An additional off-calendar day would be added each year to bring the total up to 365 days. However, this calendar would still contain a significant number of the same type of problems associated with our current calendar.
The simplest and next most logical calendar system would be the 13-month calendar. Each month has 28 days (4 weeks) and each year has an extra day not associated with any month or day of the week. It would be an off-calendar day. In addition, there would also be an off-calendar leap day (once every 4 years). Each month would always begin on a Sunday and would always end on a Saturday, exactly 28 days later.
A huge benefit resulting from this calendar system is that each numerical date will always be the same day of the week. Never again would anyone need to ask, “What day of the week does the 12th fall on this month?” Countless missed appointments, misunderstandings, confusion and frustration could be avoided. The largest potential drawbacks are that each year would have an uneven number of months, possibly making multiplication and addition a little more confusing and, with 13 months, such an ‘unlucky number’ may make many people feel uneasy. Each month would also contain a Friday the 13th. But people should ‘grow up’ and get used to it. Or, to avoid the Friday the 13th dilemma, we could have the months begin on a Monday and end on a Sunday. This way, there would always be a Friday the 12th and a Saturday the 13th. An additional benefit is that Saturdays and Sundays could then be accurately called the “weekend”.