Sales of real estate are the primary guide to the county's mass appraisal system. Winona County uses a computerized mass appraisal system that uses the sales and the property characteristics that are unique to each parcel to arrive at a market value. Major property characteristics used to determine value on homes include the square footage, number of bathrooms, number of bedrooms, age and condition, basement finish, garage size, the presence of a fireplace, and the value of the land.