Windows 10's user share growth slowed significantly in September, but by the month's end approximately 110 million customers were running the new OS, data released today signaled.

According to U.S. analytics company Net Applications, Windows 10's user share -- a measure of the fraction of unique users who ran the OS when they went online -- grew 1.4 percentage points in September to 6.6%.

Microsoft launched Windows 10 on July 29, making September the second full month that the upgrade for Windows 7 or Windows 8.1 devices was available to download and install.

Data: Net Applications Windows 10 powers about 110 million personal computers, but is dwarfed by older editions, including the retired Windows XP and the perception-plagued Windows 8.

September's user share increase was substantially smaller than August's record setting 4.8 percentage points.

Windows 10 accounted for 7.3% of all Windows devices in September, a slightly higher number than its raw user share number because Windows powered "just" 90.5%, not 100%, of all systems tallied by Net Applications. During September, Windows 10's share of all Windows devices climbed by 1.6 percentage points.

Net Applications' data represented 110 million Windows 10 PCs, assuming a total of 1.5 billion Windows devices globally, the figure Microsoft typically trumpets.

Microsoft has not publicized a Windows 10 download or installed data point since late August, when it said that 75 million devices worldwide were running the OS.

Net Applications' Windows 10 user share portrait backed up the findings of another analytics developer, Ireland's StatCounter, which has also portrayed the OS's growth as slowing after its first month of availability.

By StatCounter's measurements, Windows 10 gained 5.9 percentage points of usage share -- more of an activity indicator, as it counts web page views by OS -- in the first four weeks after its launch. During the most recent four weeks, or from Aug. 31 to Sept. 27, Windows 10 grew by a much smaller 1.4 points.

Net Applications' numbers also validate the slowdown in a different way. During the final three weeks of August, an average of 1.8 million devices were added to Windows 10's rolls daily. But in September, the average daily increase dropped to less than half of that, to about 794,000 devices.

Even so, Windows 10 continued to best Windows 7's performance during a similar stretch. In 2009, the then-new OS had accumulated a 6.2% share of all Windows personal computers through its second full month, or more than a point under Windows 10 at the same post-launch moment.

With about 110 million devices now running Windows 10, Microsoft is at the 7% mark toward reaching its goal of putting the OS on 1.5 billion systems by mid-2018.