The von Klitzing constant ,  R_K = h/e², where h is Planck's constant and e is the charge of the electron.  The conventional value of this quantity was adopted by international agreement on January 1, 1990 to establish a standard for the ohm, R_{K - 90} = 25,812.807 ohms.

The von Klitzing Constant is represented with units of Ohms.

Notes

This constant is specified with a standard uncertainty (standard deviation) of: 0.0000084 `Omega`

The von Klitzing Constant is a component element of the definition of the Quantum Hall effect, also known as quantized Hall resistance.  Materials that exhibit the quantum Hall effect have a Hall resistance equal to R_K/n, where n is either an integer or a rational fraction.

The von Klitzing constant, RK = h/e2 = 25,812.807449(86) [[Ω]], is named in honor of von Klitzing's discovery of the quantum Hall effect, and is listed in the National Institute of Standards and Technology Reference on Constants, Units, and Uncertainty. The inverse of the von Klitzing constant is equal to half that of the conductance quantum value.