A square inch is a unit of area. It is the size of a square that is one inch on a side. It is 1/144th of a square foot, or exactly 6.4516 square centimeters.
A square centimeter, or square centimetre, is a unit of area. It is the size of a square that is one centimeter on a side. It is equal to 1/10,000th of a square meter, or approximately 0.155 square inches.