Wal-Mart discount department stores vary in size from 51,000 square feet to 224,000 square feet, with an average store covering about 102,000 square feet. Wal-Mart Supercenters stock everything a Wal-Mart discount store does, and includes a full-service supermarket. Wal-Mart Supercenters vary in size from 98,000 to 261,000 square feet, with an average of about 197,000 square feet. Wal-Mart has displayed exceptional growth over the past decade and its AA S&P investment grade credit rating carries strong appeal for real estate investors.