Dirt Away Pressure Cleaning, charges pressure washing, pressure cleaning & softwashing by the square foot, typically between $0.12 to $0.35. Many pressure washing companies also charge minimums, typically anywhere between $100 and $350. Square feet can be calculated by multiplying the length of the surface by the width. Linear square feet, or the length of commonly power washed areas such as gutters or fences, typically are priced slightly higher. The more square feet a power washing service has to power wash, the cheaper per square foot the costs will be.