Kodak Used a Calendar That Had 13 Months

Here’s a random but interesting piece of photo-related trivia: did you know that Kodak used a calendar that had 13 months? It was called the “International Fixed Calendar“, and was proposed by a guy named Moses B. Cotsworth in 1902. The system divided each year into 13 months of 28 days each, with one or two days each year not belonging to any month. The extra month was named “Sol”, and appeared between June and July. Although it was never officially adopted by any country, Kodak founder George Eastman became a huge supporter of the new calendar, and instituted it as the official calendar of Kodak in 1928. It would remain the company’s calendar of choice until 1989. Because of this, an alternate name for the calendar is “the Eastman plan”.

Image credit: Calendar Advice by brandoncripps

  • Happy_Tinfoil_Cat

    That’s so cool! I’ve always called that calender the “Davidian calender” because I thought I invented it. Besides the “Sol” and “Leap” days, every 100 years you need to add in a “Century” day.

  • Ralph Hightower

    I think the International Fixed Calendar would be confusing. I can’t remember that childhood rhyme about the number of days in a month, so I use the knuckle method.

  • Chris

    In other interesting news, did you know the Beatles invented the 8 day week?

  • Spider- Man

    and a hard days night…

  • Ranger 9

    They may not bother with the month of Sol and so forth, but to this day, a lot of companies use a marketing/sales calendar consisting of thirteen 4-week months, often just called “period 1, period 2,” etc. to avoid confusion. The advantage is that since each period has the same number of weeks, it’s easy to make accurate comparisons of month-to-month sales etc… which may be part of the reason Eastman liked it.

  • David Eckard

    What, no 91 day four month calendars for business?

  • Cynergist

    I really don’t think this is unusual.

    While working for Accenture I’ve worked in finance for a number of large international firms, all of which have used a thirteen month calendar. For accounting purposes 13 periods, each exactly 4 weeks long, is very sensible.

  • Bruce Grant

    At Big Yellow, the months were actually referred to as “periods,” as in “We’ll be releasing the new Instamatics in Ninth Period.” Most Kodakians kept a small card at the ready in their shirt pocket to translate Kodak dates into those that the rest of the world (including their families…and, truth be told, they themselves) thought in. July 4 was Eighth Period 17.

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  • Brandon Schilling

    Businesses use this and similar calendars all the time! I work for one of the nations largest retailers, 340,000 employees and $85b in revenues and we use a similar calendar. It is a 13 period calendar, with 4 weeks per period with one period having an extra day. This is commonly used in business so that you can compare sales, costs, etc from one period to another. It’s not very effective to compare calendar months as the days vary too much and they don’t all start at the beginning of a week. This is Accounting 101 stuff.