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Resistor Color Code Calculator
Decode 3, 4, 5 and 6-band resistors or work backwards from a value, with every colour named in words and the answer checked against E6 to E192.
🔒 This tool runs entirely in your browser. Your files are never uploaded to a server.
Resistance
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Every band is named in words as well as shown as a colour, because reading these codes depends on telling red from brown from orange — the exact discrimination that red–green colour deficiency makes unreliable, and that affects roughly one man in twelve. If you are unsure of a band, measure the resistor with a multimeter; the colours are a label, not a measurement.
How to use it
- Count the bands first — three, four, five or six changes what each one means.
- Read from the end furthest from the gold or silver stripe.
- Pick each colour by name; the drawn resistor shows what you have entered.
- Check the preferred-series verdict. If it fails, re-read the bands — and if the resistor reads as a real part from the other end, the tool says so rather than leaving you to spot it.
- Copy the result, or switch to Value → bands to go the other way as a four- or five-band code.
The code itself
4 bands digit · digit · multiplier · tolerance 5 bands digit · digit · digit · multiplier · tolerance 6 bands digit · digit · digit · multiplier · tolerance · tempco yellow violet red gold 4, 7, × 100, ±5% → 4.7 kΩ brown black orange gold 1, 0, × 1000, ±5% → 10 kΩ brown red black brown 1, 2, 0, × 10 → 1.2 kΩ
Note the third example: on five bands the third stripe is a digit rather than the multiplier, so the same physical colours mean something different. Counting first is the whole trick. Resistors are also not made in every value — they are made at the preferred series, a logarithmic ladder chosen so consecutive values are about a tolerance band apart: ±20% is E6 (10 15 22 33 47 68), ±10% is E12 (adds 12 18 27 39 56 82), ±5% is E24 (adds 11 13 16 20 24 30 36 43 51 62 75 91), ±2% is E48, ±1% is E96, and ±0.5% and tighter is E192. So 4.7 kΩ is an everyday E12 part, 4.75 kΩ is a real E96 1% part, and 2.5 kΩ is in none of them — not a real part. That gives a free error check: if a reading comes out at 2.5 kΩ, 4 kΩ or 7 kΩ, something has been misread, because nobody manufactures those. The tool checks every decode against the whole ladder from E6 to E192 and names the series the answer belongs to, or warns when it belongs to none — checking only E12 and E24 is not enough, since a five-band precision part such as 4.75 kΩ is an ordinary E96 value that a calculator stopping at E24 would wrongly call a misread. Every band is also named in words as well as shown as a colour: this coding scheme asks you to distinguish red from brown from orange, often under poor light, and red–green colour deficiency (which affects roughly one man in twelve) makes exactly those three colours unreliable, so a calculator built only from swatches reproduces the original design's worst feature. The drawn resistor confirms what was entered rather than being the only way to enter it. Working backwards takes a resistance and gives the code as a four- or five-band pattern, and also snaps to the nearest value that actually exists in the series that tolerance is really stocked in — asking for 3 kΩ at ±5% returns the nearest stocked E24 neighbour rather than dutifully encoding a resistor that cannot be bought.
FAQ
Which end of the resistor do I read from?
Start at the end furthest from the tolerance band — gold and silver are only ever tolerance, so if you can see one, it goes last. On a resistor with no gold or silver, the wider gap before the final band marks the tolerance end. Reading backwards is one of the two classic errors, and it usually produces a value that is not a real part, which this tool will tell you.
How do I know I read the bands correctly?
Check the answer against the preferred series. Resistors are only manufactured at standard values, and which ladder applies depends on the tolerance: E6 at ±20%, E12 at ±10%, E24 at ±5%, E48 at ±2%, E96 at ±1%, and E192 tighter still. So 4.7 kΩ is real, the precision part 4.75 kΩ is real, and 2.5 kΩ is not. If the decoded value is in no series at all, you have almost certainly misread a band, and the tool says so rather than presenting a plausible-looking number.
Why do the bands mean different things on a 5-band resistor?
Because the extra band is a third significant digit, added for precision parts. So on four bands the third stripe is the multiplier, while on five bands the third stripe is a digit and the fourth is the multiplier. Counting the bands before you start reading is not optional.
What is a 3 band resistor?
A resistor with no tolerance band. Two digits and a multiplier, and the missing fourth band means ±20% by convention — the loosest grade, made only at the six E6 values. Set the band count to three and the tool reads it that way, rather than making you pretend the tolerance band is there.
What is the color code for a 1k or 10k resistor?
1 kΩ ±5% is brown, black, red, gold; 10 kΩ ±5% is brown, black, orange, gold — the same two digits with the multiplier moved up one step. As five-band 1% parts they become brown, black, black, brown, brown and brown, black, black, red, brown. Type the value into Value → bands to get either form.
What is the sixth band?
Temperature coefficient, in parts per million per kelvin — how much the resistance drifts as the part heats up. Brown is 100 ppm/K, red 50, and so on down to 1 ppm/K for grey. It only matters for precision analogue work; for most purposes you can read a six-band resistor as a five-band one and ignore it.
I find these colours hard to tell apart.
You are far from alone, and it is a real design flaw in the standard rather than a failing on your part. Red, brown and orange are the hardest set, and red–green colour deficiency affects roughly one man in twelve. Every band here is named in words as well as shown, and if you are unsure the honest answer is to put a multimeter across it — the colours are a label, not a measurement.
Can it work backwards from a value?
Yes — switch to value-to-bands, enter a resistance, and it gives the four-band code. It also snaps to the nearest manufactured value and tells you when what you asked for is not a standard part, which saves ordering something that does not exist.
How we compare
| Feature | Online Tool Store | DigiKey | All About Circuits | Calculator.net |
|---|---|---|---|---|
| Checks the value against the preferred series (E6 to E192) | ✓ | ✗ | ✗ | ✗ |
| Three-band resistors | ✓ | Four to six | Four to six | ✓ |
| Flags a resistor that has been read from the wrong end | ✓ | ✗ | ✗ | ✗ |
| Works backwards, snapping to the series stocked at that tolerance | ✓ | Value entry, unsnapped | ✗ | ✗ |
Checked in September 2026 against digikey.com's resistor colour code calculator, allaboutcircuits.com/tools/resistor-color-code-calculator and calculator.net/resistor-calculator.html. All three decode the bands correctly; the differences above are in what they do with the answer afterwards. Reads the code both ways, names every colour so it works if you cannot separate red from brown, and checks the answer against the values that are actually manufactured. It reads a label, though — only a multimeter tells you what the part in front of you really is.