I really doubt anyone living on Alderaan said, "Happy Galactic New Year! Out with 1 BBY, and.. oh wait, it's 0 BBY. That means we get blown up this year!"

Just like I doubt the people in the 4th dynasty of Egypt wrote in their diaries that they finished the pyramids of Gaza in 2500 BC.

So, what system of measurement was in place galactically before BBY/ABY, and in which year of that calendar did the Battle of Yavin take place?

Also, I have to assume the "year" is defined according to Courusant's year? Obviously, planets all have differing rotational and orbital periods, so I would assume they also would have their own local timekeeping in place along side the galactic time, but that would be pretty irrelevant, unless you live there, of course.

I've placed my campaign a bit before Alderaan gets destroyed, and I don't want to tell the players that the current galactic year is "a few years (or months) before the Battle of Yavin."

For my own purposes, I use After the Treaty of Coruscant (ATC) as the galaxy's calendar in my campaigns. It puts the various years nicely in the 3600s, which sounds appropriately sci-fi. You can also use the Ruusan Reformation as a starting point, which has 0 ABY as 1000 RR or so.

For my players, though, I usually keep it vague and give it to them in months of time before or after a major canon event, i.e. A New Hope. If they ask for specifics I happily give them.

Imperial Founding is also a popular one, particularly among imperial factions. It does result in very small numbers though.

http://starwars.wikia.com/wiki/Galactic_Standard_Calendar

http://starwars.wikia.com/wiki/Timeline_of_galactic_history

http://starwars.wikia.com/wiki/Timeline_of_the_Galactic_Civil_War#0_ABY

Though, these do follow the EU, there is a treasure trove of info here.

In my campaign I use the Great Re-synchronization as the galactic standard, though in some VERY pro imperial areas they use Imperial Founding.

So, in mine, the Death Star was destroyed near the end of the 3rd month of year 35 say the 23 for the sake of argument, or 35:3:23. One of my players has even printed out a calendar and has when Empire Day is, when the start of our campaign was, tracks all days in hyperspace and on planetside, etc. Even has our characters birthdays marked on the calendar. LOL.

The old Star Wars Adventure journal had a date system they used in their NewsNets articles.

Could always go with 15 years since the end of the Clone Wars like they did to an extent with Star Wars Rebels since that leaves your players guessing as to when the Battle of Yavin happened.

I go with BoE (Birth of the Empire). I think that´s the most fitting.

So 19 BBY = 0 BoE

By the way, I don't think anyone in the Star Wars universe would actually use "ABY" or "BBY" as a measure of time or date. I think that is just an abstraction for those of us outside the universe.

I am using the Re-Synch, too, so that players can't determine major events too easily, due to unfamiliarity.

I always though the BBY was weird - oh sure, after the New Republic Resistance beat the Empire at Endor and assumed power I could see it. But when Palpatine was in power? Hell no.

Basing something off of the end of the clone wars/birth of the Empire - call it Empire Day or Galactic Unification Day - would make much more sense.

whenever I use a year in star wars it gets translated to ABY or BBY. Unless it is some silly archaic backwater planet that doesn't keep track of that.

By the way, I don't think anyone in the Star Wars universe would actually use "ABY" or "BBY" as a measure of time or date. I think that is just an abstraction for those of us outside the universe.

I think this guy hit it on the nose. For in universe measurement, there's nearly an infinite number of ways to do this. But telling your players what the year is ABY/BBY, especially those that are well informed of where things happen ABY/BBY, may actually give them a better idea on the overall mood of the scenario and galaxy that you as a GM has created. That is of course, you plan to stick with the general events of those dates without major changes.

By the way, I don't think anyone in the Star Wars universe would actually use "ABY" or "BBY" as a measure of time or date. I think that is just an abstraction for those of us outside the universe.

I think this guy hit it on the nose. For in universe measurement, there's nearly an infinite number of ways to do this. But telling your players what the year is ABY/BBY, especially those that are well informed of where things happen ABY/BBY, may actually give them a better idea on the overall mood of the scenario and galaxy that you as a GM has created. That is of course, you plan to stick with the general events of those dates without major changes.

Oh, I think it very well exists. In the New Republic Era that is. It is totally plausible that they started the calculation of time anew after the defeat of the empire. Maybe not in the Rebellion era, it is more likely they started the calender a new after the fall of the empire and agreed that they retroactively reboot the calender on the Battle of Yarvin. So, after the founding of the new republic, they had a meeting or whatever and said right after: So, we are now in the year 5 ABY. In real earth history, one can find similar rebootings.

I find it very likely (although I don´t know really) that Christ himself didn´t consider his year of birth as Year 0, other people had done that.

I think this is a very strange discussion. Of course the measure of years hadn´t been used before the Battle of Yarvin and as I have guessed before, maybe even not from the Rebels not right after it. (And so, it is very well possible that it is not used in EotE).

So, they had used another measurement. I think the founding of the Empire very plausible, because the Empire would like to A) mark a new era, B) would like to distance itself from the corrupt Republic, C) this year mark many important historical events: End of the Clone wars, Restrukture of the Republic, defeat of the Jedi. A megalomanic like Palpatine would see this as a totally new era.

Another possibility is that they didn´t touch the old Republic calendar, maybe to suggest the people of the Galaxy that everything is still "normal". So, there would be the year 25,000 something.