So, being the nerd I am, I was recently working on an Imperial Time converter (mainly so I could post thinks like "Captain's Log, Stardate 1 024 898.M41". As I mentioned, nerd).

(also, if anyone is interested in playing with it, it can be found here on jsfiddle. The working page appears in the lower right quadrant).

Anyways, what I ran into is you really can't convert our time to Imperial with out a computer program, at least without doing some calculations. The main issue is that the Imperium doesn't track days (why would they? Most planets don't have a 24 hour day), or months.

Instead they break a year down into 1000 units, and count those. So July 1 = 50% of the way through the year = 500 on the Imperial Calendar. So 0 500 014.M3 is July 1, 2014. And I largely agree with the system. It makes sense to use earth years and millennia for synchronization, but not days and months.

That further got me thinking, ship days really shouldn't be 24 hours either. Look at real world submarines, they operate on an 18 hour day with 3x6 hour shifts.

Now assuming people on a ship don't want to have to break out their calculators every time they need to write a date down, I'm assuming the ship would operate on something a bit more predictable in terms of their calendar, trying to get as close to a 24 hour day as possible. This gives us two possibilities:

A 333 day year with ~26 hour days, and a leap year every three years. So each day increments the calendar 3 ticks.

A 500 day year with ~18 hour days. No leap years. So each day increments the calendar 2 ticks.

After doing a fair amount of math, I'm strongly in favor of the 500 day year. In a 333 day year months, weeks, and shifts are all a nightmare, and you have that leap year. Bonus points to the 18 hour day because that is what submarines do today.

So, going with a 500 day year, I'm torn on months and weeks, primarily because the various RT rulebooks occasionally refer to them, and it's easier on the GM if that doesn't change. If we leave 12 months in a year, each month is 41-42 days.

But if we're fine with changing months, we can have 10x50 day months in a year, with 10 days in a week.

Finally, shifts. As I mentioned, real world submarines have 18 hour days. Each day as 3x6 hour shifts. So you are on a 1/3 on 2/3 off work schedule. They do this because most submarine work is important, requires 100% attention, dangerous, and extremely monotonous. And any mistakes can threaten the entire ship. 6 hour shifts are the longest it is safe to have someone focus on monotonous tasks before they start missing things.

At first I wasn't for this on an Imperial ship. After all, horrible working conditions are a pretty core part of the fluff of 40k. On the other hand, this is a ship, and a big part of the poor working conditions on a ship is the boredom and isolation, not the hours. Even the rule book makes mention of this. And a Rogue Trader ship (and most military ships) is going to be more focused on efficiency and ship safety than, say, the IG. These ships are ancient holy relics. So maybe they would focus on taking care of them. Besides, we can still abuse the ratings mercilessly.

So this is what I think I'm settling on as at least one good candidate for a ship schedule:

500 day year, 50 day month, 10 day week, 18 hour day, 3x6 hour shifts per day.

Obviously there are other possible sensible configurations (I mentioned 333). But I think it's safe to assume that a 365 day year with 24 hour days just doesn't work very well on an Imperial starship, especially when combined with the standard Imperial Dating system.

So thoughts? Critiques?

Addendum: I realized, I should make it clear that I did NOT write the javascript code for the actual date conversion, someone else did. I just implemented it to make a date converter. Don't want to take credit from someone else.

A point that no one talks about in the 40K universe (because they have no reason to talk about it) is that Holy Terra is located smack near the Galactic Core, not at all where Earth is in the Milky Way Galaxy. It might've been moved there during the Dark Age of Technology, it might be an upstart imposter, it might be the actual birthplace of humanity and we are all a lost colony of Terra waiting for rediscovery by Imperial forces. Or Tyranids.

Anyway there's no guarantee that an Imperial Day - or even an Imperial Year - is the same thing that we have. I tried to do something like this for our group, but I eventually decided for simplicity that we run on a 24 hour Earth day, and have a 1,000 day Year so everything is broken up into Metric time nicely. It does imply people live a lot longer, but most PCs have access to rejuvenat treatments and awesome medicine, and most bondsmen die of radiation poisoning so it all sort of works out.

I do really like your conversion tool though, although the timekeeping swamp that was the 13th Black Crusade makes it clear that Imperial Dates will go up to 999.999.M41, so "officially" there are 1,000 days in a year.

I'm going to show my dull nerdism way of figuring things out:

Typical year = 365 days.

24 hours in a day = 8760 hours in a year.

60 minutes in an hour = 525600 minutes in a year.

60 seconds in a minute = 31536000 seconds in a year.

Now to reverse the procedure to find an Imperial "unit". Not day or week, just a unit....

31536 seconds in a unit.

3600 seconds in an hour (60x60).

Divide 31536 by 3600 = 8.76 hours

or to put it another way....8 hours 45 minutes and 36 seconds

Make of that what you wish, but that is how I will be keeping track of my Imperial dates and times.

Though each planet will have local times too.

I do really like your conversion tool though, although the timekeeping swamp that was the 13th Black Crusade makes it clear that Imperial Dates will go up to 999.999.M41, so "officially" there are 1,000 days in a year.

That's only true if you consider each tick of the "year fraction" column to be a day. But the entry on Imperial Dates in the 5th edition rule book just calls it "year fraction" and indicates it just represents how much of year has past, not actual days. So Jan 1, 12:01am is 000 and Dec 31, 11:59:59 is 999. Each tick doesn't have to represent a full day. On earth each day will actually increment the "Year Fraction" column 2-3 ticks.

My 500 day system just assumes there are 2 ticks every day. I suppose you could treat every day as a tick, but that leaves you with ~9h days, which I think is a bit awkward.

A point that no one talks about in the 40K universe (because they have no reason to talk about it) is that Holy Terra is located smack near the Galactic Core, not at all where Earth is in the Milky Way Galaxy. It might've been moved there during the Dark Age of Technology, it might be an upstart imposter, it might be the actual birthplace of humanity and we are all a lost colony of Terra waiting for rediscovery by Imperial forces. Or Tyranids.

Anyway there's no guarantee that an Imperial Day - or even an Imperial Year - is the same thing that we have. I tried to do something like this for our group, but I eventually decided for simplicity that we run on a 24 hour Earth day, and have a 1,000 day Year so everything is broken up into Metric time nicely. It does imply people live a lot longer, but most PCs have access to rejuvenate treatments and awesome medicine, and most bondsmen die of radiation poisoning so it all sort of works out.

I must be looking at different maps than you. Looking at this set of maps of our location in the galaxy and comparing it to this set of 40k maps (both are links to google image searches) it looks to me like earth is pretty much in the same place as both, though if you have different sources I would be interested to see them.

I believe it's been noted several times that year 0 in 40k is still measured to be around the death of Christ, but that they know longer know why they measure time in such a fashion. It's also been noted that our time period is M3 (was M2 14 years ago).

Everything seems to indicate they count their years the same way we do. Though if there is evidence to the contrary, I would be very interested in seeing it. That, after all, being the whole point of this thread.

I'm going to show my dull nerdism way of figuring things out:

Typical year = 365 days.

24 hours in a day = 8760 hours in a year.

60 minutes in an hour = 525600 minutes in a year.

60 seconds in a minute = 31536000 seconds in a year.

Now to reverse the procedure to find an Imperial "unit". Not day or week, just a unit....

31536 seconds in a unit.

3600 seconds in an hour (60x60).

Divide 31536 by 3600 = 8.76 hours

or to put it another way....8 hours 45 minutes and 36 seconds

Make of that what you wish, but that is how I will be keeping track of my Imperial dates and times.

Though each planet will have local times too.

Yeah, that's what I got too, which was the big reason I decided sticking with a 365 day year didn't make a whole lot of sense. You end up with an odd incrementing system of: Mon Tue Wed Thur = 001 004 006 009, and basically need a calculator to figure anything out day to day, because days don't map to Imperial Units in any meaningful way.

My only comment would be that if you take a human and isolate them from time keeping devices and natural light sources (in a cave without a clock and only lamps to use) we all eventually settle into about a 25 hour day. The natural process of sleep and waking tied to dawn and dusk is important, and is biologically relevant. Grav-plates and void shields may help with long term low gravity and cosmic radiation effects, but the biorhythms tied to the rotation of the earth are long ingrained in the human animal, and can cause massive problems if disrupted for too long.

There's a good chance that the Imperials of the 41st millennium are no longer baseline humans. There was a period of unmitigated technological use, widespread genetic engineering is not crazy.

Might also explain why the human genome seems so malleable in 40k, even without the presence of warp magicks.

Also, thanks for this, I needed a converter.

A point that no one talks about in the 40K universe (because they have no reason to talk about it) is that Holy Terra is located smack near the Galactic Core, not at all where Earth is in the Milky Way Galaxy. It might've been moved there during the Dark Age of Technology, it might be an upstart imposter, it might be the actual birthplace of humanity and we are all a lost colony of Terra waiting for rediscovery by Imperial forces. Or Tyranids.

No, I don't think this is correct. Terra is where it's always been: on the western spiral arm of the galaxy. The Solar Segmentum is actually pretty much just the western spiral arm, and the Ultima Segmentum covers about 75% of the rest of the galaxy. The Segmentum Pacificus is pretty empty in comparison.

Have a look at this map:

http://www.dakkadakka.com/gallery/110555-Galaxy.html

No, I don't think this is correct. Terra is where it's always been: on the western spiral arm of the galaxy. The Solar Segmentum is actually pretty much just the western spiral arm, and the Ultima Segmentum covers about 75% of the rest of the galaxy. The Segmentum Pacificus is pretty empty in comparison.

Have a look at this map:

http://www.dakkadakka.com/gallery/110555-Galaxy.html

For some reason I thought 40K Terra was closer to the Galactic Core than our Earth, but I haven't been able to find any proof of this so I'll put it down to a crazy dream I had that I failed to distinguish from reality.

No, I don't think this is correct. Terra is where it's always been: on the western spiral arm of the galaxy. The Solar Segmentum is actually pretty much just the western spiral arm, and the Ultima Segmentum covers about 75% of the rest of the galaxy. The Segmentum Pacificus is pretty empty in comparison.

Have a look at this map:

http://www.dakkadakka.com/gallery/110555-Galaxy.html

For some reason I thought 40K Terra was closer to the Galactic Core than our Earth, but I haven't been able to find any proof of this so I'll put it down to a crazy dream I had that I failed to distinguish from reality.

Whose to says it was really just a dream? In the land of the mad, the sane man is king. Or, is he really mad and everybody else is sane?

Famous Quote: Is there an indelible line dividing sanity from insanity, or do they change, one into the other, at the slightest turn of events?

No, I don't think this is correct. Terra is where it's always been: on the western spiral arm of the galaxy. The Solar Segmentum is actually pretty much just the western spiral arm, and the Ultima Segmentum covers about 75% of the rest of the galaxy. The Segmentum Pacificus is pretty empty in comparison.

Have a look at this map:

http://www.dakkadakka.com/gallery/110555-Galaxy.html

For some reason I thought 40K Terra was closer to the Galactic Core than our Earth, but I haven't been able to find any proof of this so I'll put it down to a crazy dream I had that I failed to distinguish from reality.

Whose to says it was really just a dream? In the land of the mad, the sane man is king. Or, is he really mad and everybody else is sane?

Famous Quote: Is there an indelible line dividing sanity from insanity, or do they change, one into the other, at the slightest turn of events?

This quote would be much better if it was the way I had initially read it, and was referring to an inedible line.

For those who do not like messing around with java, I've made an Excel tool to help you create and manage Imperial Timestamps for your campaign.

There is also a Google Docs online version for those with Excel-aversion

I know I'm using the check-bit incorrectly, but I need greater detail than timesegments of 8,76 hrs