Wirecora resistor guide
How to Read a 4-Band Resistor Color Code
Read a 4-band resistor by identifying its first two digits, multiplier, and tolerance, with a complete 220 ohm worked example.
Direct answer: A 4-band resistor uses bands one and two for significant digits, band three for the multiplier, and band four for tolerance. The separated tolerance band normally marks the right-hand end.
Band-by-band explanation
- Band 1 · First digitRed
- Band 2 · Second digitRed
- Band 3 · MultiplierBrown
- Band 4 · ToleranceGold
The Gold tolerance band is read at the right-hand end.
How it works
- Orient the resistor so the separated tolerance band is on the right whenever its spacing makes that direction clear.
- Join the first two color values into a two-digit significant number.
- Apply the third-band multiplier, then use the fourth band to calculate the minimum and maximum resistance.
Practical example
Red, Red, Brown, Gold gives digits 2 and 2, a ×10 multiplier, and ±5% tolerance. The result is 220 Ω with an expected range from 209 Ω to 231 Ω.
Common mistakes
Check these points before relying on a color-code reading or component substitution.
Gold and yellow are not interchangeable: gold is metallic and can be a multiplier or tolerance, while yellow is a digit or multiplier color.
Reading from the tolerance end reverses the roles and often produces an impossible or misleading sequence.
Related resistor values
Open a worked color-code page generated from the same resistor engine as the calculator.
Related guides
How to Read a 5-Band Resistor Color Code
Decode a 5-band resistor using three significant digits, its multiplier, and tolerance, with guidance for precise resistance values.
Resistor Tolerance Explained with Practical Ranges
Learn what resistor tolerance means, how to calculate minimum and maximum resistance, and why tolerance is not the same as accuracy in every condition.
Frequently asked questions
Short answers to questions that commonly arise with this resistor topic.
What does the fourth band on a resistor mean?
It states the manufacturing tolerance, which defines the permitted percentage above and below the nominal resistance.
Is a gold band ever a significant digit?
No. Gold can represent a ×0.1 multiplier or ±5% tolerance, but it is not a digit color.
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