The council says keeping them open from 8am until 9pm seven days a week is possible because of self access technology.
43% of Sutton’s residents have a library membership card and borrow a collective 880,000 books a year.
The authority says 70% of these books were either picked up or dropped off using the self-service system.
Study sessions are a hit too, with over 24,000 bookings last year.
60,000 people also attended cultural activities or events in that time.