A Reckoning of the Year
Thirteen months of twenty-eight days
Every month identical: four exact weeks, beginning on a Sunday and ending on a Saturday, in every month of every year. The year is anchored to the winter solstice and counted from Jericho. What the orbit will not divide evenly is set aside into an Intermission that belongs to no month at all.
Download the library → MIT licensed, no dependencies
How It Works
The Gregorian year resists arithmetic. Its months run from twenty-eight days to thirty-one, no month holds a whole number of weeks, and the same date falls on a different weekday each year. The Q Calendar gives that up in exchange for a year you can reason about.
Thirteen months of exactly twenty-eight days is three hundred and sixty-four days — four weeks a month, fifty-two weeks a year, with nothing left ragged. The structure is perfectly regular, and all the irregularity the orbit forces on us is pushed into one place.
Because every month is four whole weeks, the day of the week is a function of the day of the month alone. Day 1 is always a Sunday and day 28 always a Saturday, in every month of every year. Nothing needs to be looked up.
This is the real break from the Gregorian week, which runs unbroken across year boundaries. The Q week restarts each year instead.
A Q year begins on Gregorian December 21, the winter solstice — fixed to that calendar date rather than to the true astronomical moment, which wanders across December 20 to 22. A fixed date is an approximation, but one that keeps the arithmetic exact and reproducible.
The one or two days left over once the thirteen months are spent. They belong to no month and to no week, so they carry no weekday at all, and the week resumes after them. A common year has one; a leap year has two. They are marked days in their own right — the year's own holiday, standing outside everything the rest of it is measured by.
Leap years need no separate rule. The length of a year is simply the distance from one solstice anchor to the next, so the Gregorian leap rule is honoured automatically.
Four a year: the first full moon after each solstice and each equinox. Where the turning points are fixed by the Sun, the Summits are set by the Moon against them, so they move — anywhere from hours to a full lunar month after the event that calls them.
Occasionally the moon is already close enough that a Summit falls on the same day as its equinox. The calendar marks both.
The year is anchored to December 21 as a calendar date, but the solstice itself is an instant, and it drifts across December 20 to 22. The marked solstices on this page are computed for the moment they actually occur, so in some years the Winter Solstice does not sit on the anchor that opens the year — and a Q year can contain two of them, or none.
That is the approximation the calendar was built on, made visible rather than hidden.
A Q year is numbered for the Gregorian year it ends in, not the one it starts in: Q 12026 runs from Gregorian 2025‑12‑21 to 2026‑12‑20. That is what keeps the two legible against each other — they agree for three hundred and fifty-four days of a common year, and part company only over December 21 to 31, which already belongs to the following Q year.
The count begins at 10000 BCE, taken from Jericho: the oldest continuously settled place we know of, and among the first anywhere that people built walls, stored a harvest and lived by a shared reckoning of the seasons. It predates writing by thousands of years, so nothing from it was recorded — but the organisation it required could not have worked without a calendar of some kind.
Ten thousand years leaves the last four digits of a Q year equal to its Gregorian year. Gregorian 2026 reads as Q 12026.
| Month | No. | Gregorian span | Notes |
|---|---|---|---|
| March | 1 | Dec 21 – Jan 17 | Opens the year on the solstice |
| April | 2 | Jan 18 – Feb 14 | |
| May | 3 | Feb 15 – Mar 14 | |
| June | 4 | Mar 15 – Apr 11 | Contains the spring equinox |
| July | 5 | Apr 12 – May 9 | |
| August | 6 | May 10 – Jun 6 | |
| September | 7 | Jun 7 – Jul 4 | Contains the summer solstice |
| October | 8 | Jul 5 – Aug 1 | |
| November | 9 | Aug 2 – Aug 29 | |
| December | 10 | Aug 30 – Sep 26 | |
| January | 11 | Sep 27 – Oct 24 | Contains the autumn equinox |
| February | 12 | Oct 25 – Nov 21 | |
| Quenary | 13 | Nov 22 – Dec 19 | No Gregorian counterpart |
| Intermission | — | Dec 20 | Outside every month and every week |
Take It With You
The Q Calendar is a real library, not just this page. It is released under the MIT licence — use it, change it, ship it in anything you like, commercial or not, as long as the copyright notice travels with it. No dependencies, no attribution beyond that notice, nothing to sign.
For .NET 8 projects. Carries the library, its XML documentation and the licence. Not on nuget.org — install it from wherever you save it:
dotnet add package QCalendar --version 0.1.0 --source .
QCalendar.dll and QCalendar.xml, if you would
rather reference an assembly directly than go through NuGet. The
.xml is what gives you IntelliSense, so keep the pair together.
The whole project: the library, its 111 tests, a console harness and a
Razor web app. dotnet test QCalendar.sln runs green out of the
archive. Read this one if you want to know why the calendar works the way it
does — the reasoning is in the doc comments.
The port that draws this page, plus the astronomy module behind the solstices, full moons and Master Summits. Works in a browser or under Node, with no build step. This is the same code the page above is running.
The JavaScript is a port of the C# and is held to it: the two are checked by emitting the same 77,133 dates from each and comparing hashes. The astronomy is checked against Meeus's published worked example and against four total lunar eclipses. If you find a date where they disagree, that is a bug worth hearing about — QPublishingSupport@gmail.com.