Resistor Color Code Calculator
A resistor is an electrical component regulating the flow of current in a circuit. To prevent damage to sensitive components from a voltage overload, a resistor can be used in series with that component, creating a voltage drop and protecting the component from harm. Circuit design engineers can use resistors to control both the voltage and amperage at a particular point in a circuit.
Many resistors have color-coded bands which identify varying resistance values and tolerances. This resistor color code calculator is designed to help identify and calculate values on your resistors.
How To Read 3- to 6-Band Resistor Colors
Resistors are painted with three to six bands which indicate resistance, tolerance, and sometimes the temperature coefficient of resistance. The bands are read from left to right, with the tolerance band being often printed at a wider gap from the other bands to distinguish reading direction. Gold or silver bands are always located at the right-most end as they are only used for multiplier and tolerance bands.
In 3-band resistors, the first two bands represent the first two significant digits of the resistance value in Ohms. The third band is the multiplier. While a fourth band, tolerance, is not available, the tolerance is always ±20%.
For 4-band resistors, the first two bands represent the first two significant digits of resistance. The third band is the multiplier and the fourth band is the tolerance.
For 5-band resistors, the first three bands represent the first three significant digits of resistance, followed by the multiplier band, which is then followed by the tolerance band.
Finally, for 6-band resistors, the first three bands represent the three digits of resistance, followed by the multiplier band, then followed by the tolerance band. The final band represents the temperature coefficient of resistance (TCR), which is the change in resistance per unit resistance as the temperature changes by 1 degree C. The TCR is measured in ppm/°C units.
|Color||Bands 1, 2, 3||Multiplier||Tolerance||Temperature Coefficient (ppm/°C)|
|Black||0||x 1 Ω||0||±250|
|Brown||1||x 10 Ω||±1%||±100|
|Red||2||x 100 Ω||±2%||±50|
|Orange||3||x 1,000 Ω||±0.05%||±15|
|Yellow||4||x 10,000 Ω||±0.02%||±25|
|Green||5||x 100,000 Ω||±0.5%||±20|
|Blue||6||x 1M Ω||±0.25%||±10|
|Violet||7||x 10M Ω||±0.1%||±5|
|Gray||8||x 100M Ω||±0.01%||±1|
|White||9||x 1B Ω|
Examples of Measuring Resistor Color Bands Manually
In the 6-band resistor example pictured above, with a brown first band, black second band, red third band, blue fourth band (multiplier), gold fifth band (tolerance) and green sixth band (temperature coefficient), the resistance is calculated using the following values:
- First band, brown = first digit “1”
- Second band, black = second digit “0”
- Third band, red = third digit “2”
- Fourth band, blue = multiplier with a power of 1 million
- Fifth band, gold = tolerance of ±0.5%
- Sixth band, green = ±20
Resistor Value = 102,000,000 Ω ±0.5% @ ±20 ppm/°C
It is believed that these calculations are accurate, but not guaranteed. Use at your own risk!