Resistor Color Code Calculator
Decode a 4-band or 5-band resistor color code into its resistance value and tolerance.
Assumptions used in this calculation
- Standard 4-band color code: Uses the IEC 60062 color-to-value mapping for digit, multiplier and tolerance bands as printed on the resistor body.
- Reading direction: Assumes bands are entered left-to-right in the standard reading order, with the tolerance band (gold/silver) identified as the last band.
About this calculator
Reading a resistor's value straight off its color bands is one of the more error-prone rituals in electronics, the standard IEC 60062 color code assigns numeric values to ten colors, and mixing up which band is the multiplier versus the tolerance, or misreading a similar shade like violet for grey, easily produces a resistor value off by a factor of ten or more. This calculator removes the guesswork: select the color of each band (two or three significant-digit bands, a multiplier band, and a tolerance band) for either a 4-band or 5-band resistor, and it decodes them into the resistance in ohms plus the tolerance percentage, formatted in the usual kΩ/MΩ notation. It's especially useful when sorting through a mixed parts bin, verifying a resistor before soldering it into a sensitive circuit, or teaching the color code to someone new to electronics, without needing a multimeter or memorized mnemonic on hand.
Worked example
Brown-Black-Red-Gold
Result: 1 kΩ ±5%
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