To read a resistor’s value, identify the color bands, decode the significant digits, multiplier, and tolerance, then calculate the resistance in oh
Reading Resistor Values Using the Color Code
Resistor color codes are used to indicate the resistance value, tolerance, and occasionally the temperature coefficient of a resistor. To read the value of a resistor using the color code, follow the steps below:
Step 1: Identify the Color Bands
Typically, a resistor will have four, five, or six colored bands. The first two or three bands represent the significant digits of the resistance value, the next band represents the multiplier, and the last band represents the tolerance. For five and six-band resistors, the additional band represents the temperature coefficient.
Step 2: Decode the Significant Digits
Using the color chart, assign a numerical value to the first two or three bands as follows:
- Black – 0
- Brown – 1
- Red – 2
- Orange – 3
- Yellow – 4
- Green – 5
- Blue – 6
- Violet – 7
- Gray – 8
- White – 9
Step 3: Decode the Multiplier
Assign a multiplier value to the next band, as follows:
- Black – 1
- Brown – 10
- Red – 100
- Orange – 1,000
- Yellow – 10,000
- Green – 100,000
- Blue – 1,000,000
- Violet – 10,000,000
- Gray – 100,000,000
- White – 1,000,000,000
- Gold – 0.1
- Silver – 0.01
Step 4: Calculate the Resistance Value
Multiply the significant digits obtained in step 2 by the multiplier obtained in step 3. The result is the resistance value in ohms (Ω).
Step 5: Decode the Tolerance
Assign a tolerance percentage to the last band, as follows:
- Brown – ±1%
- Red – ±2%
- Green – ±0.5%
- Blue – ±0.25%
- Violet – ±0.1%
- Gray – ±0.05%
- Gold – ±5%
- Silver – ±10%
- No color – ±20%
Now you have successfully decoded the resistance value and tolerance of the resistor using the color code.
