Decode 4, 5, and 6-band resistor color codes. Click color bands to calculate resistance value and tolerance with visual preview.
Four stripes on a resistor body encode digits, a multiplier, and a tolerance, and this tool reads them for you: pick a 4, 5, or 6-band layout, click each stripe's color, and it returns the value in ohms with tolerance and, for six bands, the temperature coefficient. The third stripe is the step most people trip on: it is a multiplier - a power of ten - not a third digit. Red, violet, orange means 27 times 1,000, not 272. A visual preview of the resistor shows the code you have assembled as you click.
A concrete input and expected output from the current implementation.
Input
4-band: Red / Violet / Orange / Gold
Expected output
27 kohm +/-5% (acceptable range 25.65-28.35 kohm)
Red and violet are digit bands 2 and 7; orange is the multiplier band, meaning x1,000, so the value is 27 x 1,000 = 27,000 ohm. Gold marks +/-5% tolerance, which puts the acceptable range at 25.65 to 28.35 kohm.
The significant-digit bands follow the IEC 60062 table: black 0, brown 1, red 2, orange 3, yellow 4, green 5, blue 6, violet 7, gray 8, white 9. The next band is the multiplier: the same colors mean powers of ten from 10^0 to 10^9, gold and silver mean 0.1 and 0.01. Four-band codes use the first two stripes as digits; 5 and 6-band codes use the first three.
After the multiplier comes the tolerance stripe: brown +/-1%, red +/-2%, gold +/-5%, silver +/-10%, and no stripe at all means +/-20%. The tool reports the resistance and the full acceptable range by multiplying the nominal value by (1 +/- tolerance). A sixth stripe on 6-band parts adds a temperature coefficient in parts per million per kelvin, telling how much the resistance drifts with heat.
It is the temperature coefficient: how much the resistance changes per kelvin of temperature, in parts per million. A 10 ppm/K band on a 10 kohm resistor means 0.1 ohm per degree, about 10 ohm across a 100-degree swing. Note that this band's color table is less standardized than the others, so a few manufacturers assign colors differently.
Band count tracks precision. Four-band resistors carry two significant digits and usually 5-10% tolerance - values from the E12 and E24 series. Five-band parts add a third digit so they can hit the finer E48 and E96 value steps, and they typically pair with 1% or tighter tolerances. If a resistor has five or six bands, treat it as a precision component.
The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.
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