Officially, hardness testing loads are expressed in Newton (N). However, historically, loads were expressed in kilogram-force (kgf), gram-force (gf), or pond (p). The correlation between kgf, kp, and N is: 1.0 kgf = 1,000 gf = 1.0 kp = 9.81 N. The term micro hardness testing is usually used when indentation loads are below or equal to 1 kgf.