I commute 12 miles each way and the amount of time it takes can depend on a lot of factors. How well I slept the night before, headwinds or tailwinds (they can be strong either way), stop lights, slowing for areas where I have to be aware of people opening their door into traffic, personal motivation for maintaining a certain speed...

It can take anywhere from 40 minutes to a little over an hour to get to work. Rides home always take longer but those are for me to enjoy...times be dammmed.