How much data (i.e. traffic) does Google speech recognition use?

How much data upload/download does Google voice recognition use to deal with a query? I would like to use it to dictate notes, some of which could potentially get quite long, so I need to make sure I can do that with an affordable data plan.

Not sure exactly how much, but it's not a lot. Even using it for quite a few voice commands during the day my data report for the Google App shows only a couple Megs of data used. Plus, you can always download offline packages to avoid using data for supported languages.