Online home valuation tools all rely on algorithms to determine an estimate. These algorithms are usually limited to calculating a home’s worth based on square footage, number of bedrooms and bathrooms, basic amenities like a garage, lot size, and comparing it to the price that similar homes sold for recently in the area. These estimates can be overly simplistic and not factor in important things like key upgrades, curb appeal, and school districts, so they’re often a good place to start, but are not very accurate.