Rent Increase for lease Renewals

[Swathi Vijayakumar]

Hi I'm a new landlord trying to navigate through this process. I'm about to go through a lease renewal for one of my tenants. I know rents in the area have gone up. In the past I've just used Zillow to determine what fair rent is. Are there any resources that I can use to determine how much I can increase my current tenants rent? I know there are rules based on County. 

Thank You!