Where WordPress download numbers really come from


Photo credit: Ryan Imel

Photo credit: Ryan Imel

I fancy talking about WordPress download numbers. I do it a lot. But why not, right? With a growing user base and more and more people using WordPress every release, it’s fun to see those numbers go up.

But nearly every time I bring up download counts someone asks about what exactly is counted. Does it count dashboard upgrades? How about Fantastico or cPanel upgrades? I didn’t know, so I reached out to the WordPress.org folks to find out more.

What counts?

Otto told WPCandy that the WordPress download counter counts ZIP downloads from WordPress.org. This includes normal dashboard upgrades, he said, because they also download the ZIP file.

When a host (WordPress-centric or otherwise) upgrades all of their users, he said, then those likely are not counted because all the updates are done using a single ZIP file. The same goes for Fantastico and other control panel systems, since the upgrades are based on their own copy of the WordPress ZIP.

Otto said if he had to guess — a “pull-it-out-of-my-ass-guess” he called it — “eleventy percent of sites are upgraded that way”, meaning in a way not counted by the download counter.

Just the changes, please

WordPress version 3.2 brought partial downloads to the platform for the first time, thanks to an improvement to the automatic update system that release. This way deltas, or only the modified files of the minor release, would be the only thing downloaded.

The move to minor point release deltas was in the interest of speed and reliability rather than bandwidth, though the change did save over 1.5 TB of bandwidth in the first couple of days.

Deltas affect the download count the same way normal downloads do, though the counts are saved separately when archived.

Bandwidth. Lots of bandwidth.

In another of my favorite Otto moments, he told WPCandy the strain of serving up millions of WordPress ZIP downloads is “probably what we in the industry call a ‘metric shit-ton’ of bandwidth.” Scientifically speaking, of course.

Photo credit: Ryan Imel

Photo credit: Ryan ImelPictured: science.

The downloads themselves, Andrew Nacin said, are served off the web nodes as the rest of the WordPress.org website. Things like api.WordPress.org, stats processing, and SVN servers are on their own; he estimated the entire grid at 25 servers.

Napkin math

At the time of this writing the WordPress download counter reads 924,460. It’s going at a few copies of download every second, based on my quick glance for a few seconds. It’s at 924,618 now.

We’ll say it’s at one million downloads, since it will likely hit that before the end of the day anyway. And it makes the math simple. At a download size of 5.2 MB, WordPress.org will have served up 5,200,000 MB or approximately 5 terabytes in just a couple of days.

“WordPress.org will have served up approximately 5 terabytes in just a couple of days.”

Or consider version 3.4, which ended its life cycle earlier this week at nearly twenty nine million total downloads. At 4.9 MB the ZIP required around 130 terabytes of bandwidth while it was available. We’re estimating, of course, since 3.4 also included two minor (delta) releases.

Historical download counts are saved, they said, but are not publicly available at the moment. For general ideas of download counts you can always browse our series on download counts that goes back to version 3.0 in 2010.

Ultimately, Nacin told WPCandy, bandwidth for WordPress ZIP downloads just isn’t much of a consideration for WordPress.org. “It receives a ton of traffic anyway.”

9 thoughts on “Where WordPress download numbers really come from

  1. For reference, by “eleventy percent” I meant that I have absolutely no idea how many sites get upgraded through means other than WordPress itself. Some, certainly. But there is really no way to tell how many. 🙂

  2. I searched google for eleventy before reading this comment.
    Question: what percentage of the total downloads for 3.4 were partial?

    • Interesting question. It only makes sense for 3.4.1 and 3.4.2 however, since all non-point-release downloads are complete downloads and not partials.

      I did the math, and I got 17% for 3.4.1 and 24% for 3.4.2. Which is pretty large considering the total numbers involved.

  3. Back when my website wasn’t running on just Centos, and I had cpanel I would never wait for cpanel to do the update for me and just trust that the code was compatibility and I never had any problems.

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