Resistor Color Code Calculator
Decode standard resistor color bands into resistance, tolerance, and temperature coefficient values. Choose between 4-band and 5-band resistors and instantly identify the resistance represented by each color.
Decode Resistor Color Bands
Select the number of bands and choose the color of each band. The calculator automatically calculates the resistance and tolerance.
Resistor Color Code Formula
A standard 4-band resistor uses two significant digits, followed by a multiplier and tolerance.
For a 5-band resistor, three significant digits are used:
How to Read Resistor Color Bands
Find the first band
Start from the end opposite the tolerance band. The first color represents the first significant digit.
Read the digits
The next one or two bands provide additional significant digits depending on whether the resistor has four or five bands.
Apply multiplier
The multiplier band tells you how many zeros or decimal places are applied to the significant digits.
Read tolerance
The final band specifies how far the actual resistance may vary from the nominal value.
Standard Resistor Color Code Table
| Color | Digit | Multiplier | Tolerance | TCR |
|---|---|---|---|---|
| Black | 0 | ×1 | — | — |
| Brown | 1 | ×10 | ±1% | 100 ppm/K |
| Red | 2 | ×100 | ±2% | 50 ppm/K |
| Orange | 3 | ×1,000 | — | 15 ppm/K |
| Yellow | 4 | ×10,000 | — | 25 ppm/K |
| Green | 5 | ×100,000 | ±0.5% | 20 ppm/K |
| Blue | 6 | ×1,000,000 | ±0.25% | 10 ppm/K |
| Violet | 7 | ×10,000,000 | ±0.1% | 5 ppm/K |
| Gray | 8 | ×100,000,000 | ±0.05% | 1 ppm/K |
| White | 9 | ×1,000,000,000 | — | — |
| Gold | — | ×0.1 | ±5% | — |
| Silver | — | ×0.01 | ±10% | — |
4-Band vs. 5-Band Resistors
4-Band Resistor
Four-band resistors use two significant digits, one multiplier and one tolerance band.
Example: Brown Black Orange Gold = 10 kΩ ±5%.
5-Band Resistor
Five-band resistors use three significant digits, one multiplier and one tolerance band. They are commonly used for more precise resistance values.
Example: Brown Black Black Red Brown = 10 kΩ ±1%.
Worked Examples
Example 1: 10 kΩ ±5%
Consider a four-band resistor with:
Brown — Black — Orange — Gold
- Brown = 1
- Black = 0
- Orange = ×1,000
- Gold = ±5%
Therefore: 10 kΩ ±5%
Example 2: 4.7 kΩ ±5%
A common four-band resistor is:
Yellow — Violet — Red — Gold
- Yellow = 4
- Violet = 7
- Red = ×100
- Gold = ±5%
Therefore: 4.7 kΩ ±5%
Example 3: 220 Ω ±5%
Red — Red — Brown — Gold
Result: 220 Ω ±5%
Example 4: 1 MΩ ±5%
Brown — Black — Green — Gold
Result: 1 MΩ ±5%
Understanding Resistor Tolerance
Resistor tolerance describes the permitted variation between the nominal resistance value and the actual resistance. For example, a 10 kΩ resistor with ±5% tolerance does not necessarily measure exactly 10 kΩ.
Higher-precision resistors can use smaller tolerance values, such as ±1%, ±0.5%, ±0.25%, ±0.1% or lower.
Temperature Coefficient
On some 5-band resistor color codes, an additional band can identify the temperature coefficient of resistance (TCR). TCR describes how much the resistance changes with temperature.
TCR is commonly expressed in parts per million per degree Celsius (ppm/°C) or ppm/K. A smaller TCR generally means less resistance change for a given temperature change.
Resistor Color Code Applications
Electronics Repair
Identify unknown through-hole resistors when repairing older circuit boards, amplifiers, power supplies and electronic equipment.
Circuit Design
Quickly verify resistor values while building prototypes, breadboard circuits and educational electronics projects.
Electronics Education
Learn how significant digits, multipliers and tolerance bands combine to identify standard resistor values.
Practical Notes
Reading Direction
The tolerance band is often separated from the other bands by a larger gap. Gold and silver bands are especially useful clues because they are normally used for tolerance or multiplier functions rather than significant digits.
If the resistor has a symmetrical appearance and the reading direction is unclear, compare the possible combinations with the expected circuit value or measure the resistor with a multimeter.
Measure When Necessary
A color code gives the nominal marked value, while a multimeter measures the actual resistance.
When measuring a resistor installed in a circuit, other components connected to it can affect the measurement. If practical, isolate at least one resistor lead before measuring.