My BS took 4 years.
My MS took 2 years.
My PhD (computational physics) took 7 years.
I was the fast one at my school. Some of my peers (high energy physics, nuclear, etc.) took 9+ years.
Then again, I met my former business partner (not at the time) while in grad school. I was 2 years into my research, and he was a fresh new assistant prof in CS. About 9 weeks younger than me. Ph.D. in CS in 3.5 years.