Recently Square Enix released their yearly Eorzea Census for 2015 and it has some really interesting numbers. They've also talked about how they have over 5 million registered accounts now. Syncaine believes this directly correlates to active subscribers, but at first blush I'd say that assumption is unsubstantiated hogwash.
However, thinking on it further, I'm not actually completely sure off-hand. So between the census and some other "registered accounts" numbers I figured I'd perform some numerical analysis to see if he's really off-base or not.
First of all, let's talk about the numbers Square Enix has released. We know they were relatively flat at 2M accounts registered from April 2014 to 2.5M accounts at December 2014. Then they jumped like crazy, reaching 4M nearly 3 months later in February 2015. Finally, they've hit over 5M in August 2015.
I still think it's fallacious to directly correlate accounts registered with active subscriptions, however, if we keep in mind FFXIV is still early in its lifecycle, and the meteoric rise in accounts created relative to the previous year, I imagine that slightly more than doubling their registered accounts in a year probably means that they've more than doubled their active subscribers. For example, if you're not generating new accounts, you're extremely likely to be losing active subscribers over time. Natural attrition as folks decide they have played enough and drop their subscription. By that logic, it's likely that the more recently someone has registered an account, the more likely it is that someone is still subscribed.
That's not a perfect assumption--there are plenty of counter-examples--but it would support Syncaine's theory to a certain extent. So why don't we take a look at the Eorzea Census 2015 data under the assumption that registered accounts is equivalent to active subscribers and see if it makes sense.
Side note: I'm going to work under the assumption of one character per account. This isn't strictly true, but given FFXIV's ability to be whatever you like on a single character, removing the necessity for alts that other games generally have, I think this is an okay assumption to make to give us an upper bound of subscriber number estimates.
Total Playing Hours
The first metric I want to look at is total playing hours of all characters. Nearly 97B hours of play time since the inception of the game. Thankfully, they give us the total playtime a year prior, which reduces this number to just under 96B hours. Seriously, like two orders of magnitude difference, which is actually pretty nuts.
It's also interesting, because the prior year their registered accounts were relatively flat from launch through August 2014. There's no way those 2M registered accounts only accounted for 823M play hours if 2.5 times that number of registered accounts were actively playing for 118x that amount by the end of the next year. This by itself would clearly show that registered accounts does not equal active accounts.
96B hours played is about 8B a month, or 266.66M a day. That would require 11M characters playing 24H a day for the full year. There is literally no way that is correct. Square Enix must have misplaced a decimal point here because that would require every registered account to have 2 characters logged in constantly.
If we assume they did misplace a decimal point, that brings us to 1.1M characters playing 24/7, or 3.3M characters playing 8 hours a day. Or 6.6M playing 4 hours a day. The 6.6M is clearly impossible (as they only have 5M registered accounts), so either Square Enix has a really impressively addicted fanbase compared to the previous year, or something is seriously wrong with the scripts harvesting their numbers. These values don't make sense.
Last year's values make sense though, because 823M hours played would mean about 0.56M characters playing 4 hours a day, and that jives with their suggestion that they had over half a million players logging in daily. A number that would make far more sense for 2015 would be in the ballpark of 5.2B total hours played, as that would mean 3M character logging in daily for 4 hours a day plus the 823M from the previous year.
This just doesn't add up. The data is clearly flawed.
Dungeon and Raid Runs
217,817 characters have entered Alexander: Gordias, the LFR-esque version of the latest raid. If Square Enix truly had 5M active subscribers, this number would be an abysmal failure. 4.35% of the population, with 0.7% ever setting foot in the Savage version. For a raid that's been out for a month and a half, that's a pretty small number.
If we look at stats for WoW's Blackrock Foundry raid nearly 2 months in at the time, we're talking about 36% of players who completed the first wing on any difficulty.
Granted, FFXIV moves a lot slower than WoW does, and there are plenty of folks who aren't yet max level, even 2 months in, but if we use that value as a basis then we're looking at a lower bound of 605,000 subscribers.
Dungeons run similarly shows a low number for potential subscribers unless an extremely significant portion of the population has no combat jobs above 50 period. Sohm Al is required for the main story past 54, and yet, it's only been attempted 450,000 times. This means, at a maximum, ~450,000 characters are through that section of the story. The actual number is probably quite a bit lower than that as multiple attempts would be made while leveling, especially through the duty roulette.
But again, FFXIV is a slower game, and I know a lot of folks who came in for the expansion and hadn't finished the 2.55 main story yet, so it's quite possible this number is low compared to the general populace of active subscribers. But even if I'm generous and say, only 25% of players have a combat job at over level 54, that's still only an upper bound of 1.8M active subscribers.
Edit: It's possible that the dungeon attempts isn't per character, but per instance spun up, which would basically multiply that 450k number by 4, bringing us to 1.8M characters through that section of the story maximum. That doesn't seem unreasonable. In fact, that kind of makes more sense given the 217k character number for entering Alexander: Gordias. With 1.4M runs of Neverreap plus Fractal Continuum combined for enough Tomestones of Law to hit the 170 ilvl requirement for Alexander, that would be under 7 runs per character if the dungeon runs were per character, which isn't quite enough to hit 170 if memory serves. That would bring the Expert Roulette dungeons to 5.6M or so runs on a character basis, which seems to be a little more reasonable as it'll be more than the Alexander populace which probably does make up more than half of those runs.
Given that, I doubt only 25% of the populace is over 54, so if we bump that to 50% that would mean an upper bound of 3.6M active subscribers.
Putting it Together
My guess for the active subscriber base is somewhere between 0.6M and 1.8M, probably closer to 1M in my opinion. If the actual number was 1M, that would mean about 21.7% of the populace have seen Alexander: Gordias, but still only puts a maximum of 45% of the populace higher than level 54 on one combat job. There's no way their total played time is remotely accurate. Frankly, I really don't think "registered accounts" is a good correlation to active subscriptions.
Edit: Given my edit above, the guess expands to between 0.6M and 3.6M, but frankly the lower bound is bound to be much higher than 0.6M given the Expert roulette dungeon runs. If the dungeon runs is per instance rather than per character, I'd double my estimate to 2M.