in si units, force is measured in newtons and area in square metres. this means stress is newtons per square meter, or n/m2. however, stress has its own si unit, called the pascal. 1 pascal (symbol pa) is equal to 1 n/m2. in imperial units, stress is measured in pound-force per square inch, which is often shortened to "psi". the dimension of stress is the same as that of pressure.