The iPhone 4S is chomping up two times as much data as the iPhone 4, according to a report from Reuters. The data comes courtesy of a study by network management firm Arieso, which attributes much of the data increase to the iPhone’s Siri feature.

But just how accurate is that Reuters report, is Siri really responsible for ‘double the data’ being used on the iPhone 4S?

The study indicates that users of the iPhone 4S also use 275% more data than owners of the older iPhone 3G. The study attributes the increase in data usage partially to the iPhone 4S’ reliance on iCloud services for backup and sync of data.

But because iCloud is available on models all the way back to the iPhone 3GS, the larger part of the data usage increase is attributed to Siri.

Because Siri uses data to stream voice commands to Apple’s servers, and also uses data to receive the results from the servers, it is perceived as a data hog. Since it is a marquee feature of the iPhone 4S and is unavailable on any older devices, it seems like it is an easy decision to blame the voice assistant for the jump in data usage.

But it’s not quite that clear-cut. Remember that the iPhone 4 numbers that the iPhone 4S is being compared to are from 2010.

That’s before Apple introduced its iCloud services at all, which can account for traffic hundreds of megabytes in size. iTunes Match, iMessage and all of the other data hungry iCloud services are likely a huge part of the increase from over a year ago.

Not only that, but the majority of the survey uses not even an iPhone 4, but an iPhone 3G as its baseline. The entire smartphone using population uses more data now than in 2010, hands down. Heck, U.S. teens alone have tripled their data usage in the last 6 months.

The data becomes even clearer when you look at the iPhone 4S in comparison to phones from other manufacturers. The HTC Desire S saw a 323% increase in data uploads over the iPhone 3G, with the iPhone 4S actually coming in under that at 320%. The Samsung Galaxy S clocked in a 199% of the 3G in download volume, with the iPhone 4S coming in higher at 276%, but not massively so.

What this boils down to is that it’s likelier that the increase is simply due to a natural upslope in data usage, along with the cloud backups (and other network services) of iCloud. But even then, it’s not much more data than any other current smartphone.

Update: Instapaper developer Marco Arment also points out that the iPhone 4S shoots higher-resolution images than the iPhone 4. That means that photos uploaded to online services that support full resolution photos or videos would also contribute to beefier data usage.