When the value can be expressed without the need for a prefix, an 'R' is used instead of the decimal separator. Additional zeros imply tighter tolerance, for example 15M0.

The code letters are loosely related to the corresponding SI prefix, but there are several exceptions, where the capitalization differs or alternative letters are used.įor example, 8K2 indicates a resistor value of 8.2 kΩ. This is not only for brevity (for example when printed on the part or PCB), but also to circumvent the problem that decimal separators tend to 'disappear' when photocopying printed circuit diagrams.

The notation also avoids using a decimal separator and replaces it by a letter associated with the prefix symbol for the particular value. Part value code Examples of resistance values R47įor brevity, the notation omits to always specify the unit (ohm or farad) explicitly and instead relies on implicit knowledge raised from the usage of specific letters either only for resistors or for capacitors, the case used (uppercase letters are typically used for resistors, lowercase letters for capacitors), a part's appearance, and the context.

The standards also define a color code for fixed resistors. This method avoids overlooking the decimal separator, which may not be rendered reliably on components or when duplicating documents. Originally meant also as part marking code, this shorthand notation is widely used in electrical engineering to denote the values of resistors and capacitors in circuit diagrams and in the production of electronic circuits (for example in bills of material and in silk screens).

4.7 k resistor color code