Tolerance is the deviation from a nominal value. It is the range in which the nominal value can move. Tolerances can be specified for physical quantities and electronic components, for circuits, measuring devices and systems
. Tolerance is a dimensionless number given as a part of the whole or as a percentage. For example, if a resistor of 100 kilo-ohms has a tolerance of 2%, then the actual value of the resistor may be between 92 kilo-ohms and 102 kilo-ohms. The value tolerance of passive components is reflected in the standard values of the E series.