Have you ever heard of a calendar of "business months" (see details inside)?

No, I never have.

Closest I’ve seen is the 4–4-5 calendar.

It’s a fiscal calendar. I would think most businesses use a fiscal calendar. Every company I have worked for did. Every retail company anyway.

I haven’t. At my business, I calculate the weekly fiscal totals we make. Whenever it’s the end of the month, I separate the days by month, so two sets of totals contain less than seven days. For example, this year I’ll be calculating the totals of July 20–26, but only July 27–31, only Aug 1–2, then Aug 3–9, etc.

@LostInParadise I think you’re describing a 52–52 Week Year – the year always ends on the same day of the week; usually, a year generally comprises 13 months of exactly 4 weeks; every “leap year,” there’s an extra week.

@JLeslie A fiscal year is simply 12 ordinary months ending on the last day of any month except December. It’s mostly C corporations that use fiscal years. Other types of entities conform to the same tax year used by most of its owners, i.e. the calendar year. For example, a partnership, owned by individuals, operates on the calendar year.

4–4-5 is used by Rolls-Royce Jet Engines. So it makes quarters that are broken into roughly three months.
Months for business are from banks and financial institutions not from manufacturing or process businesses.

Kodak followed the Eastman International fixed calendar until 1989!

“The International Fixed calendar (also known as the Cotsworth plan, the Eastman plan, the 13 Month calendar or the Equal Month calendar) is a solar calendar proposal for calendar reform designed by Moses B. Cotsworth, who presented it in 1902.[1] It provides for a year of 13 months of 28 days each, with one or two days a year belonging to no month or week. It is therefore a perennial calendar, with every date fixed always on the same weekday. Though it was never officially adopted in any country, it was the official calendar of the Eastman Kodak Company from 1928 to 1989.[2]”

I found this it looks like it is JC Penney’s fiscal calendar.

In retail every company I worked for always thought of the week as Sunday to Saturday (which meant we could schedule 4 day weekends without taking time off) and the end of the fiscal month sometimes ran into the beginning of the next month. That’s what we called it anyway. The fiscal year ended the end of January at the stores I worked at as shown in the link.

@dxs , I think part of the motivation for having exact number of weeks was to make it easy to determine monthly labor costs. The downside of the system is that it is hard to make monthly comparisons when some months have 4 weeks and some months have 5 weeks. It is also hard to make comparisons for the same month across different years because the same month will have 4 weeks in some years and 5 weeks in other years.

@LuckyGuy , That seems like a very logical way of doing things. Accountants would love that calendar. The simplest way of handling the extra day or two in a year that do not belong to any month or day of the week would be to make them holidays, which I am sure everyone would go along with. There are good psychological reasons for putting the extra days of the year in the summer, just as there are currently good reasons for making February the shortest month. My biggest objection is that it makes life more interesting to have the same day of the year fall on different days of the week.

@LostInParadise For us, we compare weekly totals and weekends. By comparing them, I’ve successfully found a pattern to determine the busiest weekends and weeks.
I also add up the monthly totals, and I’ll do this by adding all of the July segments (for this year, the three complete weeks and the two semi-weeks). The only minor problem with this is that comparing months can change based on where the weekends fall because weekends are when we are busiest. For instance, in that last July week, it’s Sun to Thurs, which aren’t nearly as busy as Fri & Sat, Aug 1 & 2. So I have to also add that week up separately if I want to compare the week. If July started two days later, we would have made significantly more in the month because there’d be 5 weekends instead of 4, but in turn we get an extra weekend in August.

@LostInParadise The retail fiscal calendar (maybe that is the same as the 4–4-5 calendar people mentioned here, I never learned that name) lines up the 4 week months and the 5 week months so they can be better compared. I think the 5 week months were March, June, September, December, but my memory might be wrong. Every few years there is an extra 5 week month in January. Having the month start on Sunday and end on Saturday also helps for sales comparison sake, because often weekends are heavy in business in retail. It also helps keep holidays even for the month, because many holidays are on Mondays.

In retail I don’t want to compare Saturday to Tuesday last year, I want to compare Saturday to Saturday. Black Friday to Black Friday.

I did a search on 4–4-5 calendars. The way that they maintain uniformity from one year to the next is to base the calendar on a 364 day year which is exactly 52 weeks. Every 5 or 6 years an entire week is added to the end of the year. For the reasons you gave, this is better for business than the calendar that I mentioned.

I found this which answers a lot of questions regarding that type of calendar. I didn’t even know about the national organization myself until I saw this website.