Triangulate two or three sources rather than trusting any single automated estimate. Zillow's Zestimate and Redfin's estimate are fine as data points, and they get less reliable the more unique or rural the property is. County assessor records and other automated models add reference points, and they tend to land reasonably close in areas with lots of similar sales. The most useful free option is usually the agent who helped you buy the home. A good local agent who knows the neighborhood can size up value in a few minutes, pulling recent comparable sales the way they would for any listing. If you need a rigorous number, say for removing mortgage insurance, settling an estate, or a divorce, order a full appraisal. That's the most defensible figure you can get. And for a truly one-of-a-kind property, no estimate settles the question. The only way to know what a unique home is worth is to put it on the market and see what a buyer will pay.