The cost of sod is said to be about 8 to 30 cents for every square foot. This is just an estimate as hiring someone to do it can lead to higher costs. By using the 30 centsper square foot, it is easy...
If you are talking about a square yard then it would be 4.20/9=0.47 per square foot. There are 9 feet in a square yard 3 feet wide X 3 feet long = 9 square feet.