Windows 10 in August set a record for a one-month increase in user share for any operating system, an analytics firm said today.

According to California-based Net Applications, Windows 10's user share -- a measure of the number of unique users who used the OS to go online -- grew 4.8 percentage points in August to 5.2% for the month.

August was the first full month that Windows 10 was available to download and install free of charge by those with Windows 7 or Windows 8.1 personal computers and 2-in-1s. Microsoft officially launched the upgrade on July 29.

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The 4.8-point user share jump was the largest tracked by Net Applications in the 11 years it has published user share data, and easily beat the previous record set in October 2011 when Windows 7 grew by 2.6 percentage points.

Windows 10 accounted for 5.7% of all Windows devices in August, a slightly higher number than its raw user share number because Windows powered "just" 91%, not 100%, of all systems tallied by Net Applications. During August, Windows 10's share of all Windows devices climbed by 5.3 percentage points.

That increase was another record for Windows, but paled in comparison to the 21.1-point increase of OS X Mavericks in November 2013 as a percentage of all Macs. That month, Mavericks' share of all editions of OS X climbed almost four times more than Windows 10's share of all Windows PCs increased in August.

The disparity illustrated how tough it will be for Microsoft to get Windows 10 onto 1 billion Windows devices within three years. While Apple has a relatively easy time convincing the approximately 80 million Mac owners to upgrade each year, Microsoft faces a rougher road because of the vastly larger Windows user base and the heterogeneous nature of both its hardware ecosystem and its customers, which include huge numbers of upgrade-wary businesses.

Even so, the number of upgraded-to-Windows 10 devices that Net Applications' data signaled is historic: The 5.7% of all Windows systems represented about 86 million machines, assuming a total of 1.5 billion Windows devices worldwide, the figure that Microsoft itself regularly touts. No other operating system has been installed at such a clip.

Windows 10 is not on 86 million systems, of course: Late last week, Microsoft claimed that the number is actually 75 million. But calculations based on Net Applications' user share did three things. First, it confirmed that Microsoft's boast was almost certainly accurate. Second, it reaffirmed that the user share data was only a guide or estimate, not a definitive count.

Finally, Net Applications' measurement validated metrics from Irish analytics vendor StatCounter, which has tracked a slowing of Windows 10's upgrade tempo in the past few weeks.

Last month, Net Applications provided weekly breakdowns of Windows 10's user share to Computerworld that showed the new OS added about 4 million machines daily in its upgrade peak during the week of August 2-8, when Windows 10 accounted for 3% of all Windows PCs.

In the three-plus weeks since August 8, Windows 10's share of all Windows PCs grew by another 2.7%, and the device representation by 41 million, for an average daily increase of 1.8 million.

At a 1.8 million-per-day pace -- as unlikely as that would be for Windows 10 to maintain -- Microsoft would reach its 1 billion goal in another 507 days, or in late January 2017, well before its minimum deadline of two years post-launch.

In other words, although statistics may be damned lies, Microsoft currently has a shot of making its 1 billion target.