Day 24: Three Calendars Nobody Uses

Tue, 16 Jun 2026 10:00:00 -0500

Yesterday we covered the Gregorian calendar. Today we’re going to talk about the attempts to replace it. There was one that almost passed at the United Nations in 1955, and one that Kodak quietly ran for sixty-one years. And there’s a current proposal from two Johns Hopkins professors that I think is interesting and worth considering.

I’m not trying to sell you on any of these. The point is that calendar reform isn’t a fringe topic, or out of the realm of possibility. It’s been taken seriously by the League of Nations, the United Nations, and the founder of Kodak, and it still shows up in the literature with a fair amount of regularity. You could come up with the best calendar design in the world and it still wouldn’t be enough. Like Daylight Saving Time, the hard part isn’t the proposal. It’s the adoption.

What’s actually wrong with the calendar

The root problem is that the numbers don’t divide cleanly. We’re stuck with 365 days because that’s what keeps the calendar aligned with the seasons, but 365 isn’t divisible by 7 or by 12. Nothing lines up, and you get awkward remainders everywhere. Three of them cause real, recurring headaches.

The same date lands on a different weekday every year. 365 divided by 7 is 52 weeks with a day left over. That leftover is why your birthday is a Wednesday this year, a Thursday next year, a Saturday the year after. Every school district redesigns its calendar. Every payroll system gets reconfigured. The cost is enormous and invisible all because of a 500 year old calendar system.

Months are unequal. 365 doesn’t divide evenly by 12 either, so months run twenty-eight to thirty-one days. February sales and March sales aren’t comparable without normalizing first.

Quarters are unequal. Q1 has 90 days, or 91 in a leap year. Q4 has 92. Ask your accountant about this irritation.

The calendar reformers' argument starts with a simple premise: none of this has to be true. What if you could design a calendar without any of these problems? Here are the attempts.

The World Calendar

The first serious modern proposal came from an American philanthropist named Elisabeth Achelis in 1930. Her design, the World Calendar:

364 days in four identical quarters of 91 days each, 13 weeks per quarter.
Each quarter is a 31-day month, then two 30-day months.
January 1 is always a Sunday. So is the start of every quarter.
Two extra days, Worldsday at the end of December and Leapyear Day at the end of June, sit outside the week. They have a date but no weekday.

By the late 1930s this had real momentum. The League of Nations debated it. The UN took it up in 1954 and 1955. India formally proposed it for adoption. It came close to a vote. It failed for one specific reason, which I’ll get to.

The Kodak version

Around the same time, a British statistician named Moses Cotsworth went further: thirteen months of twenty-eight days. Thirteen times twenty-eight is 364, with one blank day at year-end. He stuck a new month called Sol between June and July.

In this design every month is identical. Every month starts on a Sunday, ends on a Saturday, runs exactly four weeks. Cross-month comparison becomes trivial. The thing is so symmetric it barely looks like a calendar.

George Eastman, the founder of Eastman Kodak, was so sold on the industrial efficiency that he adopted it internally in 1928. Kodak ran on the thirteen-month calendar for all accounting, production, payroll, and reporting for sixty-one years, until 1989.

It worked. The hard part was the interface with everyone else. Kodak had to keep a dual calendar for billing, taxes, shipping, and contracts. The internal benefit was real, but the friction with the surrounding economy eventually wasn’t worth it. That’s the most important lesson in calendar reform. The proposal doesn’t have to be wrong to fail. It just has to fail to coordinate.

The thing that killed both of them

Both designs use blank days. A day that has a date but no day of the week, slotted outside the weekly cycle so the next year can start cleanly on a Sunday.

That innocent-looking idea is what killed reform. The seven-day week is the oldest continuously running cycle in human civilization. It predates Rome. It predates Christianity. It runs unbroken through Judaism, Christianity, and Islam for at least 2,500 years, and several major religions treat it as a sacred, inviolable obligation with the Sabbath fixed to a specific point in the cycle.

Insert a blank day, and next year’s Sabbath lands on a different civil day. Observers would have to break the civil week to keep the Sabbath, every year, on a rotating basis. The Chief Rabbi of the British Empire opposed it. So did the Vatican. So did Islamic authorities. They organized and blocked both the 1931 League vote and the 1955 UN vote. The Gregorian calendar held.

Hanke-Henry

Fast forward to 2011. Steve Hanke, an economist at Johns Hopkins, and Richard Conn Henry, an astrophysicist there, publish the Hanke-Henry Permanent Calendar.

The structure looks like the World Calendar: 364 days, four identical 91-day quarters, each quarter a 30, a 30, then a 31-day month. January 1 is always a Monday. Every date falls on the same weekday forever. Christmas is always a Sunday.

The clever part is the leap rule. No blank day. Instead, 364 days a year runs a deficit of about 1.24 days against the solar year, so every five or six years, when the gap reaches a full week, they insert a seven-day intercalary week called Xtra at the end of December. The year becomes 371 days.

Because the leap is always a multiple of seven, the weekly cycle is never broken. The Sabbath stays anchored forever. Instead of an extra non-day floating outside the week, you occasionally get an entire extra week.

The real critiques

It isn’t perfect.

Seasonal swing. Correcting in 7-day chunks instead of single days lets the solstices and equinoxes wander by up to five days over the leap cycle. Gregorian keeps them within half a day.
The birthday problem. Some dates stop existing. No January 31, no May 31, no August 31. People born on those days get mapped by convention. Small in the long view, a real political liability in the short one.
The transition. Switching retroactively is a database nightmare. Records, contracts, treaties, mortgages all need a mapping table. The cost is concentrated up front, the benefit spread over centuries.

Why the hold up

The hold up isn’t technical. The Hanke-Henry design is sensible, a good answer to a real problem, and it isn’t religious anymore either, but that was never the bar.

Politically it’s dead on arrival, for two of the reasons above. The birthday problem: good luck explaining to the public why August 31 no longer exists. And the switching cost: transitioning is expensive, it complicates everything that touches a date, and convincing people it’s worth the disruption is an enormous ask. You’re charging a real cost now for a benefit spread over centuries.

So it isn’t that the idea failed. It’s that nobody has a way to adopt it. This is the kind of thing that would need a UN resolution and a coordinated global switch, because the moment one country goes first, it recreates the Kodak problem: a dual calendar at every boundary with the rest of the world.

So the kludge keeps winning.

Tomorrow we ditch the politics and return to physics. What did Einstein’s have to say on the subject of time?

Sources

The Gregorian Calendar: Clavius, Christopher. Romani calendarii a Gregorio XIII restituti explicatio. Rome, 1603.
The World Calendar & UN History: Elisabeth Achelis and the World Calendar Association records; UN Economic and Social Council proceedings (1954-1955).
The International Fixed Calendar (Kodak): The Journal of Calendar Reform; Eastman Kodak internal archives (1928-1989).
The Hanke-Henry Permanent Calendar: “The Hanke-Henry Permanent Calendar” proposals and papers by Steve H. Hanke and Richard Conn Henry (Johns Hopkins University).

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