Why resistors are not available in equally spaced values?
Resistors commonly have values such as 2.2kW, 3.3kW, or 4.7kW and are not available in equally spaced values. This is because resistors manufacturers don’t produce values like these – why not? The answer is partly to do with the fact that resistors are manufactured to a percentage accuracy. Resistor standard values are designed to cover the entire resistance range with the minimum overlap between values. This means that, when you replace one resistor with another marked as a higher value, its actual resistance is almost certain to be larger. From a practical point of view, all that matters is for you to know that carbon film resistors: with 20% tolerance are available in multiples of: 10, 15, 22, 33, 47 and 68 with 10% tolerance are available in multiples of: 10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, and 82 with 5% tolerance are available in multiples of: 10, 11, 12, 13, 15, 16, 18, 20, 22, 24, 27, 30, 33, 36, 39, 43, 47, 51, 56, 62, 68, 75, 82 and 91 and often, having calculated the
