Non-fiction has always been free, as have children's and teen fiction.
In the past year the library collected $42,000 from its adult fiction and reserve charges and $17,000 from overdue fees.
To balance the removal of borrowing fees, the charge for late returns will more than double from 20c to 50c per day, with late CD and DVD returns rising from 50c to $1.
Council expects the changes to be "broadly neutral" in terms of revenue.
Whanganui mayor Hamish McDouall supported the change.
"History is written about the famous people but, in fact, there's history in the fiction that is written about people who don't have a voice ... it's the ordinary history of living day to day.
"I'm totally happy about this. I think it's the best news since sliced bread."