Accuracy of sites like Zillow and Redfin

[Leland Dorchester]

Hello,

I'm interested in getting started with investing in real estate and I'm curious about the accuracy of sites like redfin or zillow - Particularly the info which shows the estimated annual principal, interest, and taxes. I'm asking because I'm curious of ways that I can look at the cost/benefit of owning rentals while I do a little reading/research about investing in real estate to get started.