Free resistor color code calculator
Decode any 4-band or 5-band axial resistor to its resistance in ohms and tolerance, updated live, as you type.
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Ohm's law applies to resistive loads at DC. Results may differ for reactive loads (inductors, capacitors).
Results are estimates. Consult a professional.
How the resistor color code calculator works
The resistor color code is the ring of painted bands printed around a small axial resistor, and it tells you the part's value without any printed numbers. This calculator turns those colors back into a resistance in ohms and a tolerance percentage. You pick each band's color from the dropdowns in the order they appear on the part, choose 4 or 5 bands, and the value updates as you go. The bands are not arbitrary: each color stands for a number, and their position decides whether that number is a significant digit, a multiplier, or the tolerance.
The full resistor color code chart
One table does most of the work. Each color carries up to three meanings depending on where it sits on the body — a significant digit, a multiplier (a power of ten), and a tolerance. Black through white run 0 to 9 in spectrum order, which is the part worth memorising. Gold and silver never appear as digits; they only ever act as a fractional multiplier or as a tolerance.
| Color | Digit | Multiplier | Tolerance |
|---|---|---|---|
| Black | 0 | ×1 | — |
| Brown | 1 | ×10 | ±1% |
| Red | 2 | ×100 | ±2% |
| Orange | 3 | ×1 000 | — |
| Yellow | 4 | ×10 000 | — |
| Green | 5 | ×100 000 | ±0.5% |
| Blue | 6 | ×1 000 000 | ±0.25% |
| Violet | 7 | ×10 000 000 | ±0.1% |
| Grey | 8 | ×100 000 000 | ±0.05% |
| White | 9 | ×1 000 000 000 | — |
| Gold | — | ×0.1 | ±5% |
| Silver | — | ×0.01 | ±10% |
| None | — | — | ±20% |
Digit, multiplier and tolerance values per IEC 60062. A gold or silver multiplier divides rather than multiplies (×0.1 and ×0.01), which is how you get sub-ohm values such as 0.47 Ω.
How to read a 4-band, 5-band and 6-band resistor
The single most common error is reading the resistor backwards, because the value reverses completely if you start from the wrong end. The tolerance band sits at the right-hand end, and there is usually a slightly wider gap between it and the rest of the bands. Hold the resistor so that gap is on your right, then read left to right.
4-band resistors
Two digit bands, one multiplier, one tolerance. Read it as digit · digit · multiplier · tolerance. These are the everyday 5% and 10% parts, where the last band is almost always gold or silver — a quick way to spot which end is the tolerance.
5-band resistors
Three digit bands, one multiplier, one tolerance: digit · digit · digit · multiplier · tolerance. The extra significant figure makes them precision parts, typically ±1% or tighter. This calculator decodes both 4-band and 5-band resistors.
6-band resistors
A 6-band resistor is a 5-band part with one more band at the far right for the temperature coefficient (TCR), measured in parts per million per degree Celsius — for example brown is 100 ppm/°C, red 50, and blue 10. It tells you how much the resistance drifts with temperature and matters only for precision and high-stability designs. The first five bands are read exactly the same way, so to decode a 6-band part here you simply ignore the temperature band and enter the other five.
A worked resistor color code example
You pull a resistor from a parts drawer with four bands: brown, black, red, gold. There is a wider gap before the gold band, so that is the tolerance end and the brown band is where you start reading.
Step 1 — Read the two digit bands
Brown is the first significant digit, so 1. Black is the second, so 0. Together they spell the number 10.
Step 2 — Apply the multiplier band
The third band is red, which is a ×100 multiplier. So the resistance is 10 × 100 = 1000 Ω, which reads as 1 kΩ.
Step 3 — Read the tolerance band
The gold band is a ±5% tolerance. The calculator combines the value and tolerance into a single result string.
E12 and E24 preferred resistor values
Resistors are not made in every possible value. They are sold in standard "E-series" steps spaced so that a part's tolerance band reaches almost up to the next value, which keeps the whole range covered with as few distinct parts as possible. The E12 series has 12 values per decade and pairs with 10% parts; the E24 series has 24 and pairs with 5% parts. If a value you decode is not in these lists, recheck your reading direction — odds are the part is reversed.
| Series | Tolerance | Values per decade |
|---|---|---|
| E12 | ±10% | 10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, 82 |
| E24 | ±5% | 10, 11, 12, 13, 15, 16, 18, 20, 22, 24, 27, 30, 33, 36, 39, 43, 47, 51, 56, 62, 68, 75, 82, 91 |
Multiply any value by a power of ten to get the rest of the range (e.g. 47 → 4.7 Ω, 47 Ω, 470 Ω, 4.7 kΩ). E24 includes every E12 value plus the in-between steps.
The E12 and E24 preferred-number series are defined by IEC 60063 (current edition IEC 60063:2015), the standard for preferred numbers for resistors and capacitors. The full per-decade listings are documented on Wikipedia's "E series of preferred numbers".Common resistor color code mistakes
Most decoding errors come down to a handful of repeat offenders. Knowing them turns reading a resistor into a glance.
- Reading from the wrong end. The tolerance band goes on the right, behind the wider gap. Start from the opposite end so the digit bands come first.
- Treating gold or silver as a first digit. Gold and silver are never significant digits — they are only multipliers (×0.1, ×0.01) or tolerances (±5%, ±10%). If an end band is gold or silver, it is the tolerance end.
- Confusing similar colors. Brown can look red, and red can look orange under poor light. A faded or hot-running resistor often discolours its bands — measure with a multimeter if a color is ambiguous.
- Mixing up multiplier and tolerance. A red band means ×100 in the multiplier position but ±2% in the tolerance position. Position decides meaning, not the color alone.
- Ignoring the band count. The same colors mean different values on a 4-band versus a 5-band part, because the 5-band part has an extra significant digit. Set the band count first.
Once you have the value, the Ohm's law calculator turns it into the current and power for a given voltage, the LED resistor calculator sizes the series resistor for an LED, and the resistor calculator combines several resistors in series or parallel.
Resistor color code definitions
How accurate is this resistor color code calculator
The decoding is exact: for the colors you enter, the value is the precise nominal resistance the IEC 60062 code specifies, with the tolerance read straight from the final band. There is no rounding or estimation in the conversion itself.
The nominal value is only the centre of a range, though. A resistor's tolerance band exists precisely because the manufactured part is not exactly the printed value — a ±5% part can measure anywhere across a 10% spread, and a ±1% part across a 2% spread. Heat, ageing and the resistor's power rating all shift the true resistance over time. For anything where the exact value matters, decode the bands for the nominal figure, then confirm the part with a multimeter set to ohms.
Frequently asked questions about the free resistor color code calculator
About this resistor color code calculator
This resistor color code calculator runs entirely in your browser — pick each band's color in order, choose 4 or 5 bands, and it decodes the painted rings into a resistance value in ohms and a tolerance percentage using the IEC 60062 color code, with no printed numbers needed on the part.