Resistor colour bands identify the resistance value, tolerance, and, on some precision resistors, temperature coefficient. Each band has a specific meaning, and its position determines how the resistor’s value is calculated.
The calculator above supports standard 4-band, 5-band and 6-band resistors. Choose the band count and select the corresponding colours to calculate the resistance and its tolerance range.
Resistor Color Code Calculator
Select the colour of each band to calculate the resistor's resistance and tolerance.
Brown – Black – Red – Gold
Based on the IEC 60062 resistor colour code. Check the component manufacturer's datasheet if its markings or specifications differ.
How to Read Resistor Colour Codes
Resistor colour codes follow a standard system in which each colour represents a number or multiplier. The position of the band determines its purpose.
The bands are normally read from the end where the first band is closest to the edge. The tolerance band is usually spaced slightly farther from the other bands, helping identify the correct reading direction.
4-Band Resistors
A 4-band resistor uses:
- First band – First significant digit
- Second band – Second significant digit
- Third band – Multiplier
- Fourth band – Tolerance
For example, consider a resistor with these colours:
Brown – Black – Red – Gold
- Brown represents 1.
- Black represents 0.
- Red represents a multiplier of 100.
- Gold represents ±5% tolerance.
The calculation is:
10 × 100 = 1,000 Ω (1 kΩ)
With a tolerance of ±5%, the actual resistance can range from 950 Ω to 1,050 Ω.
5-Band Resistors
A 5-band resistor provides an additional significant digit, allowing more precise resistance values.
The bands represent:
- First band – First significant digit
- Second band – Second significant digit
- Third band – Third significant digit
- Fourth band – Multiplier
- Fifth band – Tolerance
For example:
Red – Violet – Black – Brown – Brown
- Red = 2
- Violet = 7
- Black = 0
- Brown multiplier = ×10
- Brown tolerance = ±1%
The calculation is:
270 × 10 = 2,700 Ω (2.7 kΩ)
The tolerance is ±1%.
6-Band Resistors
A 6-band resistor uses the same arrangement as a 5-band resistor, with one additional band for the temperature coefficient.
The bands represent:
- First three bands – Significant digits
- Fourth band – Multiplier
- Fifth band – Tolerance
- Sixth band – Temperature coefficient
The temperature coefficient indicates how much the resistance changes with temperature. It is measured in parts per million per degree Celsius (ppm/°C).
For example, a temperature coefficient of 50 ppm/°C means the resistance changes by approximately 50 parts per million for every 1°C change in temperature, under the specified reference conditions.
Resistor Colour Code Chart
The following table shows the commonly used resistor colour code values.
| Colour | Digit | Multiplier | Tolerance |
|---|---|---|---|
| Black | 0 | ×1 | — |
| Brown | 1 | ×10 | ±1% |
| Red | 2 | ×100 | ±2% |
| Orange | 3 | ×1,000 | ±0.05% |
| Yellow | 4 | ×10,000 | ±0.02% |
| Green | 5 | ×100,000 | ±0.5% |
| Blue | 6 | ×1,000,000 | ±0.25% |
| Violet | 7 | ×10,000,000 | ±0.1% |
| Grey | 8 | ×100,000,000 | ±0.01% |
| White | 9 | ×1,000,000,000 | — |
| Gold | — | ×0.1 | ±5% |
| Silver | — | ×0.01 | ±10% |
A resistor without a tolerance band generally indicates ±20% tolerance.
Not every colour is used for every band position. For example, gold and silver are commonly used as multiplier or tolerance bands, not as significant-digit bands.
How to Calculate Resistance
The basic formula depends on the number of significant-digit bands.
4-band resistor:
Resistance = (First digit × 10 + Second digit) × Multiplier
5-band and 6-band resistors:
Resistance = (First digit × 100 + Second digit × 10 + Third digit) × Multiplier
To calculate the tolerance limits:
- Minimum resistance = Resistance × (1 − Tolerance / 100)
- Maximum resistance = Resistance × (1 + Tolerance / 100)
The calculator performs these calculations automatically when you select the band colours.
Frequently Asked Questions
How do I know which end of a resistor to read first?
Start from the end where the first band is closest to the edge. The tolerance band is usually separated by a slightly larger gap from the other bands.
What is the difference between 4-band and 5-band resistors?
A 4-band resistor has two significant digits, while a 5-band resistor has three. The additional digit provides greater precision when specifying resistance values.
What does the gold band mean on a resistor?
Gold represents a multiplier of ×0.1 when used as a multiplier band. When used as a tolerance band, it indicates ±5% tolerance.
What does the silver band mean?
Silver represents a multiplier of ×0.01 or a tolerance of ±10%, depending on its position.
What does the sixth band represent?
The sixth band indicates the temperature coefficient of resistance (TCR), measured in ppm/°C. It tells you how sensitive the resistor's resistance is to temperature changes.
Can I use this calculator for all resistors?
This calculator supports standard 4-band, 5-band, and 6-band axial resistor colour codes. It does not decode SMD resistor markings, which use numerical or alphanumeric codes.
For surface-mount components, use our separate SMD Resistor Calculator.
Note: Colour bands can sometimes be difficult to distinguish on older or damaged components. If the resistor's value is critical to a circuit, verify it with a multimeter or the component's datasheet.
