Who would have thought WH 40k could be so educational? In writing the backstory we had to fit the campaign into WH40k canon events and so became conversant with the Imperial Dating System at Lexicanum and many variations of contemorary dating systems.

The imperial three-digit date/time group (DTG) was somewhat problematic. We first thought this was simply the ordinal date (1 – 365) but in closer reading we discovered this was a calendar year divided into 1,000 equal parts of about 8 hours and 45 minutes each. All of a sudden we were reexamining all the DTGs and years to make the blog posts consistent.

Date value table

What was kind of interesting was not being able to find an online converter to easily translate a calendar date and time into the decimal code.

In the process of writing a simple formula we discovered the differences between Julian and Gregorian Calendars, Ordinal Dates used by the military and programmers, and the Julian Date used in astronomy and liturgical (church) practices. Since we still can’t find an online converter, we thought we would post our method for converting dates to help keep time in the campaign.

We started by calculating an Ordinal Date between 1 (January 1) and 365 (December 31) Using the table from a Wikipedia article.

Or the NASA julian date converter.

We could simply multiply that number by three and call it a day, but that would yield a number up to 1095. Or an error factor of almost 10%!

It’s been more than three decades since I studied algebra, but I finally remembered that if X equals the number you’re looking for, and you want to multiply that by 365 days (we will ignore leap years for the sake  of our cranium’s structural integrity), we will want that to equal 1000; or 365x = 1000. For a factor of— 2.73926. (We also warned you this was going to be educational.)

So, if using the table, February 28 would be 31 + 28 = 59;   59 x 2.73926 = 164.8; to make it about noon round up and add one (= 166).

This should be more than accurate enough for gaming purposes, but feel free to leave a comment if you have a more accurate formula that does not involve javascripts or excel spreadsheets.

—The Gaffer

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The Corvus Cluster is a Warhammer 40K blog documenting our gaming adventures in the fantastical sci-fi universe of Games Workshop.