By Jason Snell

September 22, 2014 4:30 PM PT

How fast is that iPhone 6 processor?

Note: This story has not been updated for several years.

One of the tools I use to gauge the speed of a new iOS device is Geekbench from Primate Labs, a 99-cent app. Geekbench is a convenient and invaluable tool, but not all of its results are ironclad.

In my Macworld review of the iPhone 6 and 6 Plus, I mentioned that the A8 processor in the iPhone 6 Plus was clocked slightly higher than the processor in the iPhone 6. Today, in an exchange that started on iMore, moved to Twitter and finally relocated to email, Geekbench developer John Poole told me that Primate Labs’s data indicates that the processors on the two iPhones are actually running at the same speed.

How could this be? It turns out that Apple doesn’t provide apps with access to a device’s clock speed, so Geekbench cleverly estimates clock speed by measuring the time it takes to execute a particular function. Unfortunately, if other apps and background tasks are also taxing the processor—something that’s harder to spot on an iPhone than, say, a Mac—it can cause Geekbench to misreport the processor speed as slower than it is. In the case of my measurements of the iPhone 6, this is apparently what happened.

So, for the record: Primate Labs reports that the A8 processors in the iPhone 6 and iPhone 6 Plus appear to be running at the same clock speed. I apologize for disseminating bad data, and will approach the information I receive from off-the-shelf tools—even ones as handy as Geekbench—with more skepticism in the future.

In the meantime, I commend Anandtech’s iPhone 6 and 6 Plus benchmark story to your attention.

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