Update - October 31: We have adjusted these estimates after the release of new numbers from Sony and Nintendo.

Original Story

Getting an accurate read on how well the new generation of consoles is selling is a difficult job, and it's complicated by sporadic and sometimes vague numbers provided by the console makers themselves. After taking a dive into the most recent numbers, Ars estimates that the PlayStation 4 has sold at least 42 percent more units worldwide than the Xbox One through September. This makes Sony's system responsible for at least 59 percent of hardware sales in the two-console market (PS4 and Xbox One).

Estimating Xboxes

Determining those ratios was not a simple process. As a starting point, we used Microsoft's announcement that it had shipped five million units of the Xbox One as of mid-April. Since then, the company has only released quarterly reports on how many total Xbox systems have shipped, lumping the Xbox 360 and the Xbox One together, which obscures the new console's true market performance.

For the April to June quarter, there were 1.1 million combined Xbox shipments. For the July through September quarter, there were 2.4 million combined Xbox shipments. Add all those numbers together, and you get an absolute ceiling of 8.5 million potential Xbox One shipments through September. For the new system to hit that ceiling, though, you'd have to assume that Microsoft has shipped exactly zero Xbox 360 units in the last six months, which is obviously false.

So how many Xbox 360 units did Microsoft ship in that time? We don't know for sure, but we can try to extrapolate from the previous years' performance. From quarterly reports, we know that Microsoft shipped 2.3 million Xbox 360 units in the April to September time frame in 2013. That's down from 2.8 million during the same six-month period in 2012.

We can only presume that Xbox 360 shipments continued to fall in 2014, with the drop enhanced by the intervening release of the Xbox One. But how enhanced? Let's be generous to the Xbox One and assume that Xbox 360 sales absolutely tanked, plummeting to one-third of their 2013 levels. That would mean about 766,000 of Microsoft's 3.5 million combined Xbox shipments for April to September 2014 were taken up by the Xbox 360, leaving about 2.75 million shipments for the Xbox One in that time. Adding that estimation back in gives us 7.75 million Xbox One shipments through the end of September.

Of course, shipments to stores are not the same as sales to consumers. Maybe stores are stuck with millions of unsellable Xbox One units clogging up their warehouses. Or perhaps every single shipped Xbox One has been gobbled up by a rabid customer base, leaving store shelves bare.

The truth is somewhere in the middle, of course, as stores tend to only order shipments of consoles they expect to sell to consumers in the near future. Wedbush Morgan analyst Michael Pachter tells Ars that game retailers usually order enough product to keep their stocks full for four weeks. Thus, almost everything shipped to retailers by the end of September would usually be sold through to consumers by the end of October.

Pachter told Ars that outside of the holidays, retailers might maintain a bit less than four weeks of stock for console hardware (as opposed to software), so let's be generous and say that retailers worldwide are, on average, sitting on only two weeks of Xbox One shipments that they have yet to sell to consumers. That would mean roughly 333,000 of the last roughly two million Xbox One shipments were not yet sold through to consumers by the end of September. Subtract those from our total shipment numbers, and we get our final estimate of about 7.42 million Xbox One units sold to consumers worldwide through the end of September.

Pondering PlayStations

For the PlayStation 4, the estimation process is a little simpler. Sony announced on August 12 that it had sold 10 million PS4 units through to consumers worldwide. That announcement came 130 days after the company announced seven million sales, meaning Sony had sold an average of just over 23,000 PS4 units a day in the intervening period.

Even assuming PS4 sales absolutely cratered after that, selling half as quickly, Sony would still have sold about 560,000 additional PS4 units in the 49 days from August 12 to the end of September. Add that, and we get a floor of about 10.56 million PS4s sold through the end of September, compared to a ceiling of about 7.42 million Xbox One units sold by the same time.

Dividing those numbers out leaves us with the PS4 selling about 42 percent better than the Xbox One, with Sony's system representing about 59 percent of the two-console market. And remember, this estimate is making assumptions that are quite generous to the Xbox One and quite pessimistic for the PlayStation 4. The real ratio might be even less encouraging for Microsoft.

Why does it matter?

Is the sales lead that the PS4 has built up big enough to really skew the market for console video games? Probably not yet. Most third-party game publishers would be crazy to simply ignore over 40 percent of their potential market, and millions of potential purchases, by focusing solely on the PlayStation 4 (absent some sort of outside incentive ). This is why third-party console exclusives are much rarer than they were in the era of the original PlayStation and PlayStation 2, where Sony's systems had a dominant market share and became the de facto standard for many third-party franchises.

Microsoft might need to worry if Sony's lead keeps expanding. An Xbox One with roughly 40 percent of the worldwide market is hard to ignore. An Xbox One that is whittled down over time to 25 or 30 percent of the market make it easier for publishers to decide to pass on ports (see: publishers' reaction to the Wii U's light sales ). Already, developers like Crytek are saying they're "not 100 percent happy with Xbox One sales."

There's no guarantee that this kind of market attrition will happen, of course—the Xbox One could easily bounce back and grab more market share in the future, or at least hold on to its respectable 40-ish percent. That might require a major turnaround in consumer sentiment, though, as the PS4 has outsold the Xbox One for the last nine months in the US, and that the Xbox One is basically a non-factor in Japan, where Sony's system is selling well. Then again, Microsoft is reportedly selling a lot of Xbox One units in China this month, so maybe that new market will help buoy the system's prospects.