How to set a rent price for a long-time tenant.

[Larry Scott Hastings]

We have a couple who has rented a home from us for 20 years (long before we decided to take real estate investing seriously). We're currently renting it for $2300.

We know we need to increase rent on the property, but how much? One online estimator (Bigger Pockets) says rent should be about $2800, and another (Zillow) says $4800. That's a wide gap!

What's the smart way to determine rent on this property?

--Scott