Small resistors use color coding to present their values.
There can be three, four, five or six color coding bands on the resistor.
For three and four band resistors then it works as follows:
- You read first band from the direction where its shorter to the edge of the resistor. (Gap between 3 and 4 can also hint the reading direction)
- First two bands make up significant numbers of the resistor.
- Third band is the multiplier
- Fourth band is the tolerance.
| Color | First 2 bands | Third band | Fourth band |
|---|---|---|---|
| Black | 0 | 1 | – |
| Brown | 1 | 10 | – |
| Red | 2 | 100 | – |
| Orange | 3 | 1.000 | – |
| Yellow | 4 | 10.000 | – |
| Green | 5 | 100.000 | – |
| Blue | 6 | 1.000.000 | – |
| Violet | 7 | 10.000.000 | – |
| Gray | 8 | - | – |
| White | 9 | - | – |
| Gold | - | 0.10 | 5% |
| Silver | - | 0.01 | 10% |
If there is no 4th band then the tolerance is 20%.
So from the table above then Resistor that is Brown – Black – Orange – Gold has the values 1 – 0 and multiplier of 1000 that equals to 10 * 1000 = 10kΩ and 5% tolerance which means that the resistors actual values should only vary at most 5% from the given rating.
For five and six band resistors then it works as follows:
- You read first band from the direction where its shorter to the edge of the resistor. In five band resistor there will often be gap between 4th and fifth band (I sometimes find those resistors hard to know which side to start from as its not always obvious, but you can verify your reading with multimeter)
- First three bands make up significant numbers of the resistor.
- Fourth band is the multiplier
- Fifth band is the tolerance.
- Sixth band is temperature coefficient
| Color | First 3 bands | Fourth band | Fifth band | Sixth band |
|---|---|---|---|---|
| Black | 0 | 1 | - | 250 |
| Brown | 1 | 10 | 1% | 100 |
| Red | 2 | 100 | 2% | 50 |
| Orange | 3 | 1.000 | - | 15 |
| Yellow | 4 | 10.000 | - | 25 |
| Green | 5 | 100.000 | 0.5% | 20 |
| Blue | 6 | 1.000.000 | 0.25% | 10 |
| Violet | 7 | 10.000.000 | 0.1% | 5 |
| Gray | 8 | - | 0.05% | 1 |
| White | 9 | - | - | - |
| Gold | - | 0.10 | 5% | - |
| Silver | - | 0.01 | 10% | - |
If there is no 5th band then the tolerance is 20%.
So from the table above then Resistor that is Brown – Black – Red – Orange – Gold has the values 1 – 0 – 2 and multiplier of 1000 that equals to 102 * 1000 = 102kΩ and 5% tolerance which means that the resistors actual values should only vary at most 5% from the given rating.
If resistor has 6th band then the 6th band is temperature coefficient where brown is the most common value. (100 ppm/K) which means for a temperature change of 10 ˚C, the resistance value can change 0.1%.