About the Resistor Color Code Calculator
The Resistor Color Code Calculator decodes color bands to resistance values and encodes values back to bands. Supports the three standard configurations: 4-band (2 digits + multiplier + tolerance), 5-band (3 digits + multiplier + tolerance, for tighter-tolerance precision parts), and 6-band (adds a temperature coefficient in ppm/°C). An interactive resistor diagram lets you click each band rather than memorize the digit table.
It is built for electronics students working through their first circuits class, hobbyists picking components out of a drawer of mixed loose parts, makers fixing a board where the markings are too small to read confidently, professional EEs double-checking a part value before committing to a PCB order, and anyone who has ever wired a 27Ω pull-down where a 27kΩ was specified.
All decoding runs locally in JavaScript. Band selections, target values, and encoded outputs never leave your device. The page makes no network call after first load. Component-selection data sometimes encodes pre-launch hardware design choices; the calculator never sees them.
Standard band mnemonics (“Bad Boys Race Our Young Girls But Violet Generally Wins” or its cleaner variants) cover digits Black 0 through White 9. Orient the resistor with the wider gap (tolerance band, usually gold or silver) on the right and read left-to-right. SMT resistors don’t use color bands — they use 3- or 4-digit numeric codes printed on the body, which this calculator does not decode. For SMT, use the SMD resistor code chart (most are XX×10^Y).
Black(0) · Brown(1) · Red(2) · Orange(3) · Yellow(4) · Green(5) · Blue(6) · Violet(7) · Grey(8) · White(9)
| Color | Digit | Multiplier | Tolerance | Temp Coeff |
|---|
Shows closest values from E12, E24, E48, and E96 standard resistor series.
| Series | Nearest Value | Difference |
|---|---|---|
| Select colors or enter a value first | ||
Enter a 3-digit or 4-digit SMD code to decode its resistance.
Need a non-standard value? Find two E24 resistors that combine to approximate your target.
How to Read Resistor Color Codes: A Visual Guide
Every through-hole resistor uses colored bands painted on its body to indicate its resistance value, tolerance, and sometimes temperature coefficient. Reading these bands is a fundamental electronics skill. Start by orienting the resistor so the bands are grouped toward the left side — the tolerance band (typically gold or silver) sits on the far right with a slightly wider gap. For a 4-band resistor, the first two bands represent the significant digits, the third is the multiplier (number of zeros), and the fourth is tolerance. For example, Red–Violet–Orange–Gold means 27 × 1,000 = 27,000 Ω (27 kΩ) with ±5% tolerance. This calculator lets you click colors directly on an interactive resistor diagram, so you can match what you see on a real component and get the value instantly.
4-Band vs 5-Band vs 6-Band Resistors
The number of bands determines precision. A 4-band resistor gives two significant digits and is the most common type found in hobby kits and consumer electronics. A 5-band resistor adds a third significant digit, providing higher precision — typical in professional and precision circuits where values like 47.5 kΩ matter. The 6-band variant adds a temperature coefficient band that indicates how much the resistance changes per degree Celsius (measured in ppm/°C). Brown (100 ppm/°C) is the most common temperature coefficient. Higher-precision applications like instrumentation amplifiers and measurement bridges often require 6-band resistors with tight thermal specs. This tool automatically adjusts the SVG diagram and selector rows when you switch between band counts.
Standard Resistor Values: E12 and E24 Series
Resistors are not manufactured in every possible value. Instead, the electronics industry uses standardized series defined by the IEC 60063 standard. The E12 series contains 12 values per decade (1.0, 1.2, 1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6, 6.8, 8.2) and covers ±10% tolerance resistors. The E24 series adds intermediate values for ±5% components. Higher series like E48, E96, and E192 serve tighter tolerances (2%, 1%, and 0.5% respectively). When you need a specific resistance that does not match a standard value, you can combine resistors in series (add values) or parallel (reciprocals add) to approximate it. The premium combination finder in this tool does exactly that — showing you two standard resistors that combine closest to your target.
Resistor Tolerance: What It Means in Practice
Tolerance specifies the acceptable range of actual resistance compared to the nominal value. A 1 kΩ resistor with ±5% tolerance (gold band) can measure anywhere from 950 Ω to 1,050 Ω and still be within spec. For most hobbyist projects, 5% or 10% tolerance is perfectly fine. But in precision analog circuits — voltage dividers for ADC references, Wheatstone bridges, active filters — even small resistance errors compound and affect accuracy. That is where 1% (brown band) or tighter tolerances become essential. Keep in mind that tolerance is a manufacturing guarantee, not a measurement: your specific resistor might be dead-on nominal even if its tolerance band says ±5%. A multimeter is always the final arbiter of actual resistance.
SMD Resistor Codes vs Through-Hole Color Bands
Surface-mount (SMD) resistors are too small for color bands, so they use a printed numeric code instead. A 3-digit code like “472” means 47 × 10² = 4,700 Ω. A 4-digit code like “4702” means 470 × 10² = 47,000 Ω. The last digit is always the multiplier (number of zeros). An “R” in the code marks the decimal point: “4R7” means 4.7 Ω. The EIA-96 system uses a two-digit number plus a letter for 1% tolerance SMDs, which is less intuitive but compact enough for tiny 0201 packages. Whether you are working with through-hole or surface-mount components, this tool handles both coding systems so you can quickly verify values during assembly or troubleshooting.
Looking for related tools? Try our Ohm’s Law Calculator to compute voltage, current, and power, or our Unit Converter for measurement conversions. Explore all Math & Science tools.
Frequently Asked Questions
How is a 4-band resistor decoded?
Bands 1 and 2 are significant digits, band 3 is the decimal multiplier (power of ten), and band 4 is tolerance. For example, Red-Violet-Orange-Gold is 27 * 10^3 = 27,000 ohms (27 kohm) +/- 5%.
What does a 5-band resistor add?
A 5-band resistor uses three significant digits, a multiplier, and a tolerance band. For example, Brown-Black-Black-Red-Brown is 100 * 10^2 = 10,000 ohms (10 kohm) +/- 1%.
What does the sixth band mean on a 6-band resistor?
The sixth band is the temperature coefficient, measured in parts per million per degree Celsius (ppm/C). Brown is 100 ppm/C, Red is 50 ppm/C, Orange is 15 ppm/C, and Yellow is 25 ppm/C.
What tolerance do gold and silver bands indicate?
Gold represents +/- 5% tolerance and silver represents +/- 10%. No tolerance band typically means +/- 20%. Tighter tolerances (+/- 1%, +/- 2%) use brown and red bands.
How do I remember the color code order?
Many engineers use the mnemonic Bad Beer Rots Our Young Guts But Vodka Goes Well: Black (0), Brown (1), Red (2), Orange (3), Yellow (4), Green (5), Blue (6), Violet (7), Grey (8), White (9).