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Resistor Color Code Calculator
Use this free resistor color code calculator to read the coloured bands on a resistor and find its resistance in ohms, its tolerance, and — for 6-band resistors — its temperature coefficient. Pick the colours of each band and the value updates instantly, or use the reverse mode: type in a resistance value and the calculator shows you the bands to look for.
Reverse: value to bands
4,700 Ω is yellow, violet, red, gold in 4-band code.
Your resistor
The bands on the resistor above match the colours you picked. The tolerance band (gold here) sits at the right-hand end.
How it works
A resistor is a small electronic part that limits the flow of electric current, and its value is printed on its body as coloured bands because a resistor is too small and too round for printed numbers. Each colour stands for a digit, and reading the bands from one end to the other gives the resistance in ohms. The system is the same on resistors everywhere, which is why learning the ten colours once lets you read almost any resistor you pick up.
The first bands are digits. Black is 0, brown is 1, red is 2, orange is 3, yellow is 4, green is 5, blue is 6, violet is 7, grey is 8, and white is 9. A 4-band resistor has two digit bands; a 5-band or 6-band resistor has three. The next band is the multiplier: it tells you how many zeros to add, or what to multiply the digits by. Black means times 1, brown times 10, red times 100, orange times 1,000, yellow times 10,000, green times 100,000, blue times 1,000,000, and gold times 0.1 and silver times 0.01 for resistors under 10 ohms. The band after the multiplier is the tolerance, which says how far the real resistance may sit from the printed value: gold means plus or minus 5 percent, silver means 10 percent, brown means 1 percent, red means 2 percent, and no band at all means 20 percent.
Reading a resistor is a matter of direction. The tolerance band — usually gold or silver — sits slightly apart from the other bands, near one end of the body. Start reading from the opposite end, the end where the first digit band sits closest to the edge. If you read it backwards you will get a nonsense value, often one that does not match any standard resistance at all, which is itself a useful warning sign. When the bands are hard to tell apart — red and brown, or orange and yellow, look alike in dim light — read the resistor under a bright white light and compare with the colour table below.
The sixth band, found only on 6-band resistors, gives the temperature coefficient in parts per million per degree (ppm/K). It describes how much the resistance drifts as the resistor warms up: brown means 100 ppm/K, red 50, orange 15, yellow 25, blue 10, and violet 5. A resistor rated at 100 ppm/K changes by 100 ohms for every million ohms for each degree of temperature change — a 10 kΩ resistor would drift by 1 ohm per degree. Precision circuits use low temperature-coefficient resistors so their behaviour stays steady as the equipment warms up.
Resistor colour table
Every colour and its meaning, in one place. The digit column is used by the first two or three bands, the multiplier column by the band after them, the tolerance column by the band after that, and the temperature column only by the sixth band of a 6-band resistor.
| Colour | Digit | Multiplier | Tolerance | Temp. coeff. |
|---|---|---|---|---|
| Black | 0 | ×1 | — | — |
| Brown | 1 | ×10 | ±1% | 100 ppm/K |
| Red | 2 | ×100 | ±2% | 50 ppm/K |
| Orange | 3 | ×1,000 | — | 15 ppm/K |
| Yellow | 4 | ×10,000 | — | 25 ppm/K |
| Green | 5 | ×100,000 | ±0.5% | — |
| Blue | 6 | ×1,000,000 | ±0.25% | 10 ppm/K |
| Violet | 7 | ×10,000,000 | ±0.1% | 5 ppm/K |
| Grey | 8 | ×100,000,000 | ±0.05% | — |
| White | 9 | ×1,000,000,000 | — | — |
| Gold | — | ×0.1 | ±5% | — |
| Silver | — | ×0.01 | ±10% | — |
A memory trick students use is the sentence "Black Boys Race Our Young Girls But Violet Generally Wins Silver And Gold", where the first letter of each word matches the first letter of each colour in order. It is a well-known mnemonic in electronics teaching, and it is worth learning if you read resistors often.
Worked example
Take a resistor with four bands: brown, black, red, gold — the combination the calculator shows when the page first loads. Step one: brown is digit 1 and black is digit 0, so the first two bands give the number 10. Step two: red is the multiplier, times 100, so 10 times 100 is 1,000 ohms. Step three: 1,000 ohms is 1 kΩ, because one kilo-ohm is one thousand ohms. Step four: gold is the tolerance, plus or minus 5 percent, so 5 percent of 1,000 is 50 ohms, and the real resistance of this resistor is somewhere between 950 and 1,050 ohms. The calculator shows exactly this: "1 kΩ ±5%", with the range in the line underneath.
Now try a 5-band resistor. Switch to 5-band mode and pick yellow, violet, black, black, brown. The first three bands give the digits 4, 7, 0 — the number 470. The fourth band, black, is the multiplier times 1, so 470 times 1 is 470 ohms. The fifth band, brown, is the tolerance, plus or minus 1 percent, so the real value is between 465.3 and 474.7 ohms. And in reverse: type 4,700 into the reverse box, leave the unit on ohms and the tolerance on gold, and press Find the bands. The calculator answers yellow, violet, red, gold — 47 times 100 — and sets the band selectors to match, so the resistor diagram above shows those very colours.
FAQ
What does brown black red gold mean on a resistor?
Brown is 1, black is 0, so the first two bands give 10. Red as the multiplier means times 100, so 10 times 100 is 1,000 ohms, or 1 kΩ. Gold as the tolerance band means plus or minus 5 percent, so the real resistance is between 950 and 1,050 ohms.
How do I read a 5-band resistor?
A 5-band resistor has three digit bands instead of two, then a multiplier band and a tolerance band. Read the first three bands as a three-digit number, multiply by the multiplier, and the last band gives the tolerance. For example, yellow, violet, black, black, brown is 470 times 1, or 470 ohms, with a 1 percent tolerance.
Which end of the resistor do I start reading from?
Start from the end where the first band sits closest to the edge, or from the end opposite the gold or silver tolerance band, which usually sits slightly apart from the others. The tolerance band is almost always gold or silver, so the end with the gold or silver band is the end you finish at, not the end you start at.
What is the sixth band on a resistor for?
The sixth band gives the temperature coefficient, which tells you how much the resistance drifts as the resistor heats up, measured in parts per million per degree (ppm/K). Brown means 100 ppm/K, red means 50, orange means 15, yellow means 25, blue means 10, and violet means 5. A lower number means a more stable resistor.
What do gold and silver bands mean?
As a tolerance band, gold means plus or minus 5 percent and silver means plus or minus 10 percent. As a multiplier band, gold means times 0.1 and silver means times 0.01, which is how resistors under 10 ohms are marked — for example, red, red, gold, gold is 2.2 ohms with a 5 percent tolerance.