How to Identify Resistors

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Resistors are very common components in electronic circuits of all kinds. Their function is to resist the current flowing in the circuit, and how much resistance they provide is measured in ohms. Most are printed with either a color code or an alphanumeric code to indicate their ohmic value and tolerance -- how much their resistance may vary. Learning the codes, along with using a helpful mnemonic device, will allow you to identify resistors easily.

Method 1
Method 1 of 2:

Color Coded Resistors (Axial Resistors)

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  2. These are sometimes followed by a gap, then an additional color band. [1]
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  3. The colors on the first 2 or 3 bands correspond to numbers from 0 to 9, which represent the significant digits of the resistor's ohmic value. The last band gives the multiplier. For example, a resistor with brown, green and green bands is rated at 15 mega-ohms (15,000,000 ohms). The code is as follows: [2]
    • Black: 0 significant digit, multiplier of 1
    • Brown: 1 significant digit, multiplier of 10
    • Red: 2 significant digit, multiplier of 100
    • Orange: 3 significant digit, multiplier of 1,000 (kilo)
    • Yellow: 4 significant digit, multiplier of 10,000 (10 kilo)
    • Green: 5 significant digit, multiplier of 100,000 (mega)
    • Blue: 6 significant digit, multiplier of 1,000,000 (10 mega)
    • Violet: 7 significant digit
    • Gray: 8 significant digit
    • White: 9 significant digit
    • Gold: multiplier of 1/10
    • Silver: multiplier of 1/100
  4. This represents the tolerance of the resistor. If there is no color band, the tolerance is 20 percent. Most resistors have no band, a silver band or a gold band, but you may find resistors with other colors. The tolerance color code is as follows: [3]
  5. 1 percent tolerance
  6. 2 percent tolerance
  7. 3 percent tolerance
  8. 0.5 percent tolerance
  9. 0.25 percent tolerance
  10. 0.1 percent tolerance
  11. 0.05 percent tolerance
  12. 5 percent tolerance
  13. 10 percent tolerance
  14. Several exist, so choose the one that you won't forget. Remember that the first color is black, and afterward each first letter corresponds to a color in order from 0 to 9. Some popular mnemonic devices include: [4]
    • "Bad beer rots our young guts but vodka goes well."
    • "Bright boys rave over young girls but veto getting wed."
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Method 2
Method 2 of 2:

Alphanumerically Coded Resistors (Surface Mounted Resistors)

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  1. Surface mounted resistors are rectangular in shape with leads that extend from opposite sides or the same side and are bent downward for mounting on circuit boards. Some resistors have contact plates on the bottom. [5]
  2. The first 2 or 3 represent the significant digits and the last indicates the number of 0s that should follow. For example, a resistor reading 1252 indicates a rating of 12,500 ohms or 1.25 kilo-ohms. [6]
  4. 0.05 percent tolerance
  5. 0.1 percent tolerance
  6. 0.25 percent tolerance
  7. 0.5 percent tolerance
  8. 1 percent tolerance
  9. 2 percent tolerance
  10. 5 percent tolerance
  11. 10 percent tolerance
  12. 20 percent tolerance
  13. This indicates a very small resistor, and the letter takes the place of a decimal point. For instance, a 5R5 resistor is rated at 5.5 ohms.
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  • Question
    What color is a 2.2 K ohm resistor?
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    This answer was written by one of our trained team of researchers who validated it for accuracy and comprehensiveness.
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    These resistors have a 4-band color code, with 3 red bands and 1 gold band.
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    What is the “K” in a resistor?
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    This answer was written by one of our trained team of researchers who validated it for accuracy and comprehensiveness.
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    The K stands for 1,000 ohms. This means that, for example, a 5K resistor would have a value of 5,000 ohms.
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  • Question
    What are the 4 types of resistors?
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    There are many different kinds of resistors, but the main types are linear resistors (which can be fixed or variable) and non-linear resistors. There are a variety of subtypes in each of those categories.
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      References

      1. ↑ https://www.jameco.com/Jameco/workshop/circuitnotes/circuit-notes-resistors.html
      2. ↑ https://www.digikey.com/en/resources/conversion-calculators/conversion-calculator-resistor-color-code
      3. ↑ https://www.digikey.com/en/resources/conversion-calculators/conversion-calculator-resistor-color-code
      4. ↑ https://www.arrow.com/en/research-and-events/articles/resistor-color-code
      5. ↑ https://www.diyaudioandvideo.com/Electronics/ResistorColorCodes/
      6. ↑ https://www.diyaudioandvideo.com/Electronics/ResistorColorCodes/

      About This Article

      Article Summary X

      To identify resistors, first look at the shape of the resistors to find out which type they are. Axial resistors are cylindrical with a group of color bands, while surface mounted resistors are rectangular with alphanumeric codes. For axial resistors, read the color bands from left to right which will tell you the ohmic value, multipliers, and tolerance. To help you remember each color’s value, memorize a mnemonic like “Bad beer rots our young guts but vodka goes well.” To learn more, like what numbers go with each color and how to read surface mounted resistors, scroll down!

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