Okay, here’s my language on Zillow.com from the Arizona Home Sale News resources page.

Zillow.com. You can find comps on a map. Very nice. Unfortunately, their comps are a bit old, I’m seeing 3 to 4 months after closing. Here at Home Sale News and at azcentral.com our data is only about 3 weeks after closing. Beware: Zillow.com value estimates (“Zestimates”) are not very good. For Phoenix Arizona, 28% of their “Zestimates” are off by 10 percent or MORE. Yikes! If your home is worth $200,000, there’s a 28% chance Zillow.com will tell you it’s worth more than $220,000 or less than $180,000.

UPDATE: I got that 28% figure here.

Zillow’s “zestimate” accuracy is far worse outside metro Phoenix.