Resistor Symbols

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Chapter 2 - Resistor Standards and Codes

All types of resistors have their own resistor symbols which are used when a circuit diagram is drawn. This page will explain the different standards which are used for resistor symbols and display the most common symbols.

Standards for Resistor Symbols

Several standards exist, which describe how the different components should be displayed. In the past, a lot of countries and even individual industries used their own standards, which can be confusing. Nowadays, the IEC 60617 standard is the international standard for these electronic symbols. However, local standards are still used from time to time. In general, the ANSI standard is still common in the United States. Some examples of standards which describe resistor symbols:

  • IEC 60617 (International)
  • ANSI Y32 / IEEE 315 (US) - old
  • DIN 40900 (Germany) - old
  • AS 1102 (Australia) - old

Sometimes the symbol for a particular device is different when it is used in another field of application. For example, different symbols are used in electronics than, for example, in architecture and construction. On top of this, many local deviations from the international standards exist. The following table shows the most common resistor symbols for electronics design.

Schematic Symbols

Type Abbreviation IEC (International) ANSI (US)
Fixed resistor R resistor symbol resistor symbol - US
Heater resistor   heater resistor symbol  
Variable resistors VR    
Potentiometer   Potentiometer symbol




Potentiometer symbol US




Trimming potentiometer   Trimpot symbol Trimpot symbol US
Rheostat   Rheostat symbol Rheostat symbol US
Preset resistor  


Preset resistor symbol


preset symbol US
Dependent resistors      
Photo resistor or Light dependent resistor LDR  LDR symbol  LDR symbol US
Varistor or Voltage dependent resistor  VDR



VDR symbol VDR symbol US
NTC thermistor NTC


thermistor symbol thermistor symbol american
PTC thermistor PTC


PTC thermistor symbol PTC thermistor symbol US
Magneto resistor or Magnetic dependent resistor  MDR magneto resistor symbol magneto resistor symbol US