Resistor colour code calculator
Pick the bands from left to right — start from the end the bands crowd toward, with the gold or silver band on the right. The drawing follows your picks, and you get the value, the tolerance and the range a good part should measure.
Mida fuera del circuito y sin tocar las terminales con las manos. Algunas tablas más recientes (IEC 60062:2016) dan el gris como ±0.01 % — en una pieza de precisión, consulte la hoja de datos del fabricante.
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How it works
Each colour stands for a digit, 0 to 9: black 0, brown 1, red 2, orange 3, yellow 4, green 5, blue 6, violet 7, grey 8, white 9. The first two bands (three on a 5-band part) are the significant digits. The next band is the multiplier — how many zeros to add, or gold ×0.1 and silver ×0.01 for values under 10 Ω. The last band is the tolerance: how far from the marked value the real part is allowed to be.
The old trade mnemonic is fine, but the order is also a rainbow with black and brown in front and grey and white at the back: B B R O Y G B V G W.
Worked examples
Yellow, violet, red, gold
- Digits: yellow 4, violet 7 → 47.
- Multiplier: red is ×100 → 47 × 100 = 4,700 Ω = 4.7 kΩ.
- Tolerance: gold ±5 %. 5 % of 4,700 is 235, so a good part measures 4,465 to 4,935 Ω.
Brown, black, black, red, brown (5 band)
- Digits: brown 1, black 0, black 0 → 100.
- Multiplier: red ×100 → 10,000 Ω = 10 kΩ.
- Tolerance: brown ±1 % → 9,900 to 10,100 Ω.
Preguntas frecuentes
Which end do I start reading from?
The end the bands are bunched toward. The tolerance band — usually gold or silver — sits on its own at the other end, often with a wider gap in front of it. If a band sits hard against one end, that end is the start. Turn the resistor so the tolerance band is on your right and read left to right.
What is the difference between a 4-band and a 5-band resistor?
Four bands give two digits, a multiplier and a tolerance; five bands give three digits, so the value can be stated more precisely — which is why five-band parts are usually the ±1 % and tighter ones. The multiplier and tolerance bands work the same way on both.
My meter reads a bit different from the colour code. Is it bad?
Not if the reading is inside the tolerance range this calculator shows. A 4.7 kΩ ±5 % part is good anywhere from 4,465 to 4,935 Ω. Measure it out of circuit — anything else connected across it changes the reading — and with your fingers off both leads, because your body is a resistance too.
Ver también
- Ohm’s law and power — the lesson behind this tool.
- Using your meter — the lesson behind this tool.
- Series & parallel resistance calculator — once you know what each one is.
- Ohm’s law calculator
- Using a multimeter — measuring a resistor to check it.
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