Elec Class
learn electricity hands-on
Free calculator · works both ways
Find a resistor's value from its colour bands, or the bands for a value (220 Ω, 1 kΩ, 10 kΩ…), for 3, 4, 5 or 6 bands. The color code chart and the method are just below.
From its colors, or the other way round. Live.
1/4 Pick the color of the 1st digit.
4.7 kΩ
± 5 %Actual value between 4.46 kΩ and 4.93 kΩ.
4 7 → 47
47 × 100 = 4,700 Ω
47 × 100 = 4.7 kΩ
Highlighted rows match the decoder.
| Color | Digit | Multiplier | Tolerance | Temp. coefficient |
|---|---|---|---|---|
| black | 0 | × 1 | 250 ppm/K | |
| brown | 1 | × 10 | ± 1 % | 100 ppm/K |
| red× | 2 | × 100 | ± 2 % | 50 ppm/K |
| orange | 3 | × 1 k | 15 ppm/K | |
| yellow1st | 4 | × 10 k | 25 ppm/K | |
| green | 5 | × 100 k | ± 0.5 % | 20 ppm/K |
| blue | 6 | × 1 M | ± 0.25 % | 10 ppm/K |
| violet2nd | 7 | × 10 M | ± 0.1 % | 5 ppm/K |
| grey | 8 | × 100 M | ± 0.05 % | 1 ppm/K |
| white | 9 | × 1 G | ||
| goldtol. | × 0.1 | ± 5 % | ||
| silver | × 0.01 | ± 10 % |
Highlighted: the colors of the resistor shown in the decoder.
3 bands: two digits and the multiplier, ± 20 % tolerance. 4 bands: the tolerance is added. 5 bands (precision): three digits, the multiplier and the tolerance. 6 bands: a 6th band gives the temperature coefficient.
4 steps, with the 4.7 kΩ example.
The gold or silver band, set slightly apart, goes on the right.
Yellow = 4, violet = 7: that gives 47.
Red = × 100, so two zeros: 4,700 Ω.
Gold = ± 5 %: between 4,465 and 4,935 Ω.
Exampleyellow, violet, red, gold→47 × 100 = 4,700 Ω = 4.7 kΩ at ± 5 %
The gold or silver band (the tolerance) goes on the right: it is often set slightly apart from the others. Then read from left to right, starting with the band closest to the end.
With a sentence whose words start like the colors from 0 to 9: “Bad Beer Rots Our Young Guts But Vodka Goes Well” for black, brown, red, orange, yellow, green, blue, violet, grey, white. Another clue: from 2 to 7, the colors follow the rainbow.
In last position it is the tolerance: gold ± 5 %, silver ± 10 %. In 3rd position it is a multiplier: gold × 0.1, silver × 0.01 (for values under 10 Ω).
Red, red, brown, gold: 22 × 10 = 220 Ω at ± 5 %. A 1 kΩ resistor is brown, black, red and a 10 kΩ one is brown, black, orange.
4.7 kΩ at ± 5 %: yellow = 4, violet = 7, red = × 100, so 47 × 100 = 4,700 Ω.
With 3 bands: two digits and the multiplier, no tolerance band (± 20 %). With 5 bands: three digits, then the multiplier and the tolerance; brown, black, black, brown, brown is 100 × 10 = 1,000 Ω at ± 1 %. With 6 bands: the 6th gives the temperature coefficient, for example brown = 100 ppm/K.
Common 5 % values follow the E12 series, multiplied by a power of ten: 10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68 and 82. Replace a calculated value with the closest one.
With an ohmmeter (a multimeter set to Ω), with the resistor out of the circuit. The reading should fall within the tolerance range shown by the decoder.