How much data does Siri use?
If you're worried about Siri's data usage on your iPhone 4S, you may be looking for details to make sure you don't exceed your cellular (3G / EDGE) data plan allotment each month. Now that people have been using Siri for a while, reports are in on just how much data Siri needs to work.
After testing, Ars Technica found that an average Siri task used 63 kB of data. This means that even with heavy usage (10-15 queries daily) on average Siri will use under 30 MB total for the month.
If you have a small data plan, like the AT&T DataPlus capped at 200 MB, then 30 MB amounts to a solid 15 percent of your data allotment. For users with the DataPro plan with 2 GB of usage, using Siri heavily will take up less than 2 percent of monthly data limits. For most users of Siri, data use will not be a concern, even with heavy usage of the personal assistant.