A resistor color code is a standardized set of colored bands that encode a resistor's resistance and tolerance, defined by the international standard IEC 60062. Each color stands for a digit from 0 to 9, one band is a power-of-ten multiplier, and the last band is the manufacturing tolerance. Read brown-black-red-gold and you get 1, 0, times 100, plus or minus 5%, which is 1,000 ohms (1 kΩ) at ±5%. The Best Answer Hub Resistor Color Code Calculator decodes 4, 5, and 6-band resistors, works backward from a value to the bands, and adds an Ohm's Law and LED resistor helper, all in your browser.
This guide covers what each color means, how 4, 5, and 6-band resistors differ, how to tell which end to start reading from, and the properties the bands do not encode. The tool sits in the Best Answer Hub Calculators hub STEM suite, is built and maintained by Shahbaz Ali Malik, and stays free because Best Answer Hub is funded by optional paid assessments rather than advertising.
What is the Best Answer Hub Resistor Color Code Calculator?
The Best Answer Hub Resistor Color Code Calculator is a free, browser-based electronics tool that turns colored bands into a resistance value and back. It decodes 4, 5, and 6-band through-hole resistors plus 3-digit, 4-digit, and EIA-96 surface-mount codes, and it works in reverse to suggest the bands for a target value with the nearest standard E-series option. It also bundles an Ohm's Law solver and an LED resistor calculator with wattage warnings, and a colorblind-friendly text mode, with no signup and nothing uploaded.
- 1Decodes and reverses. Bands to value for 4, 5, and 6-band and SMD codes, or a target value back to its bands and nearest E-series match.
- 2Sizes the circuit too. An Ohm's Law solver and an LED resistor calculator with current and wattage warnings, plus Arduino and Raspberry Pi presets.
- 3Readable for everyone. A colorblind text mode picks band colors from labeled dropdowns rather than relying on color vision.
What does each color mean?
Every color maps to a digit, and the same palette doubles as the multiplier. Black is 0 through white at 9 for the significant figures, the multiplier band multiplies by a power of ten, and the tolerance band gives the precision. The whole system is set by IEC 60062, and the standard resistance values themselves come from the E-series in IEC 60063 (Electronic color code, per IEC 60062).
| Color | Digit | Multiplier | Tolerance |
|---|---|---|---|
| Black | 0 | ×1 | – |
| Brown | 1 | ×10 | ±1% |
| Red | 2 | ×100 | ±2% |
| Orange | 3 | ×1k | – |
| Yellow | 4 | ×10k | – |
| Green | 5 | ×100k | ±0.5% |
| Blue | 6 | ×1M | ±0.25% |
| Violet | 7 | ×10M | ±0.1% |
| Grey | 8 | ×100M | – |
| White | 9 | ×1G | – |
| Gold | – | ×0.1 | ±5% |
| Silver | – | ×0.01 | ±10% |
Brown-black-red-gold: digits 1 and 0, multiplier times 100, tolerance plus or minus 5 percent, giving 1,000 ohms. Source: IEC 60062, worked value per ComponentsInfo.
Gold and silver appear in two places: as fractional multipliers (times 0.1 and times 0.01) and as tolerance colors (plus or minus 5% and plus or minus 10%). That is why band position, not just color, decides the meaning. The Best Answer Hub Resistor Color Code Calculator reads each band by its slot, so a gold multiplier is never mistaken for a gold tolerance.
4, 5, or 6 bands: what is the difference?
The band count tells you how many significant digits you have. A 4-band resistor uses two digits, a multiplier, and a tolerance. A 5-band resistor adds a third significant digit for tighter precision, common in 1% parts. A 6-band resistor adds a temperature coefficient band, in parts per million per kelvin, that says how much the resistance drifts with temperature (All About Circuits).
| Bands | Structure | Typical use |
|---|---|---|
| 4-band | 2 digits + multiplier + tolerance | General purpose, 5% or 10% |
| 5-band | 3 digits + multiplier + tolerance | Precision, often 1% |
| 6-band | 5-band + temperature coefficient | Temperature-stable circuits |
Which end do you read from?
Start from the end away from the tolerance band. The tolerance band, usually gold or silver, is often wider and set slightly apart from the rest, so you turn the resistor to put it on the right and read left to right (Electronics Tutorials; SparkFun). Reading a resistor backward is the single most common mistake, and because gold and silver never appear as first digits, a gold or silver band is your cue for which end is the tail.
Worked value per ComponentsInfo; reverse example per SparkFun.
Red, brown, and orange can look alike under poor light or on a dusty part, and a resistor read from the wrong end gives a completely different value. Good lighting, a magnifier, and a tool that shows the decoded value help. The Best Answer Hub Resistor Color Code Calculator highlights the reading direction and offers a labeled text mode for exactly these cases.
What the color bands do not tell you
The bands encode resistance and tolerance, and nothing else. Crucially, they do not encode the power rating: how many watts a resistor can safely dissipate is set by its physical size, since a larger body sheds more heat (Electronics Tutorials). The value is also nominal within tolerance, so a 220-ohm resistor at 5% is in spec anywhere from 209 to 231 ohms, which is why a multimeter reading 215 is perfectly fine.
The color code gives R, but a real LED circuit still needs Ohm's Law to pick the value and a wattage check. Source: Ohm's Law; formula standard.
How is Best Answer Hub different from other resistor calculators?
The difference is that it does the whole job in one place. Many free decoders are forward only, turning bands into a value and stopping there. The Best Answer Hub Resistor Color Code Calculator decodes 4, 5, and 6-band and SMD codes, reverses a value into bands with the nearest E-series match, sizes an LED resistor with a wattage check, and guides the reading direction, ad-free and with no signup.
| Feature | Best Answer Hub | Typical decoder |
|---|---|---|
| Decode 4, 5, 6-band and SMD | Yes | Often bands only |
| Reverse: value to bands + E-series | Yes | Usually not |
| Ohm's Law and LED resistor sizing | Built in | Separate tool |
| Colorblind text mode | Yes | Rare |
| Ads or signup | Neither | Some carry ads |
Try the free Resistor Color Code Calculator
Decode 4, 5, and 6-band and SMD resistors, reverse a value into bands, and size an LED resistor with a wattage check. No signup, in your browser.
Open the Resistor Color Code CalculatorFrequently asked questions about resistor color codes
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Sources
- Wikipedia, Electronic color code (IEC 60062:2016; digit, multiplier, and tolerance colors).
- All About Circuits, Resistor Color Code Calculator (4, 5, 6-band structure and tolerance values).
- Wikipedia, E series of preferred numbers (IEC 60063 preferred values, E12 / E24 / E96).
- Electronics Tutorials, Resistor Colour Code (read from the tolerance band end, left to right).
- SparkFun, Decoding Resistor Markings (worked 4.7 kΩ reverse example, tolerance band separation).
- Electronics Tutorials, Resistor Power Rating (wattage is set by physical size, not the bands).
- ComponentsInfo, 1k Ohm Resistor Color Code (brown-black-red-gold worked example).
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