Resistor Color Code Calculator
CalculatorDecode resistor color bands to resistance values or enter a value to find the matching color code. Supports 4-band, 5-band, and 6-band resistors.
| Color | Digit | Multiplier | Tolerance | TCR (ppm/°C) |
|---|---|---|---|---|
black | 0 | ×1 | — | — |
brown | 1 | ×10 | ±1% | 100 |
red | 2 | ×100 | ±2% | 50 |
orange | 3 | ×1 kΩ | — | 15 |
yellow | 4 | ×10 kΩ | — | 25 |
green | 5 | ×100 kΩ | ±0.5% | — |
blue | 6 | ×1 MΩ | ±0.25% | 10 |
violet | 7 | ×10 MΩ | ±0.1% | 5 |
grey | 8 | ×100 MΩ | ±0.05% | — |
white | 9 | ×1 GΩ | — | — |
gold | — | ×0.1 | ±5% | — |
silver | — | ×0.01 | ±10% | — |
none | — | — | ±20% | — |
About this tool
About Resistor Color Code Calculator
The resistor color code is a standard system for marking resistor values using colored bands painted directly on the component body. This tool works in both directions: given a set of color bands it decodes the resistance value, tolerance, and TCR; given a resistance value it finds the matching set of color bands. All computation runs locally in your browser — no data is sent anywhere.
Supports 4-band resistors (2 significant figures), 5-band resistors (3 significant figures, used for precision resistors), and 6-band resistors (3 significant figures plus TCR band). The decode mode updates in real time as you select colors from the visual band pickers. The encode mode accepts plain ohm values, shorthand notation (4k7, 2M2), or suffixed values (4.7k, 2.2M) and finds the exact matching color code.
Use this tool to quickly read an unmarked resistor you picked out of a parts bin, to double-check a color code before soldering, to generate resistor diagrams for documentation, or to learn the color code system. It's also handy for verifying that a resistor in a schematic matches the color bands of the part in hand.
The visual resistor diagram updates in real time as you select colors, making it easy to cross-check with the physical component. The color reference table on the same page shows digit, multiplier, tolerance, and TCR values for all 13 band colors in one view. Everything runs offline in your browser — no installation, no account, no data sent to any server.
Key Features
- 4-band, 5-band, and 6-band support
- Decode: color bands → resistance value
- Encode: resistance value → color bands
- Real-time SVG resistor diagram
- Tolerance range (min/max) calculation
- TCR (temperature coefficient) for 6-band resistors
- Full color reference table
- Accepts kΩ / MΩ shorthand in encode mode
- 100% browser-based, works offline
FAQ
Resistor Color Code Calculator — Frequently Asked Questions
How does the resistor color code work?
Each color represents a digit (0–9), a multiplier (×1 to ×1 GΩ), or a tolerance value. For a 4-band resistor: the first two bands are significant digits, the third is the multiplier, and the fourth is tolerance. For a 5-band resistor: three significant digit bands, one multiplier, one tolerance. For a 6-band resistor: same as 5-band plus a sixth band for TCR (temperature coefficient of resistance). The resistance in ohms equals the digit mantissa times the multiplier.
What is the difference between 4-band and 5-band resistors?
A 4-band resistor encodes 2 significant figures, while a 5-band resistor encodes 3. For example, a 4-band resistor can represent 47 Ω but not 47.0 Ω or 47.5 Ω — those require a 5-band. Precision resistors (±1% and tighter) are almost always 5-band or 6-band. Standard resistors from the E12 and E24 series are typically 4-band. If you see a brown-black-black first band, that's almost always a 5-band resistor (the extra black is the third digit).
What does TCR mean?
TCR stands for Temperature Coefficient of Resistance, measured in ppm/°C (parts per million per degree Celsius). It tells you how much the resistance changes with temperature. A TCR of 100 ppm/°C means the resistance shifts by 0.01% for every 1 °C change in temperature. This is only relevant for precision circuits — for most general-purpose circuits you can ignore it. Only 6-band resistors have a TCR band.
What does 'none' in the tolerance band mean?
A resistor with no tolerance band (just 3 colored bands and a gap) has a default tolerance of ±20%. These are very old or very cheap resistors rarely seen in modern electronics. If you're reading a 3-band resistor, treat it as a 4-band with the tolerance band missing and assume ±20%.
How accurate is the encode mode?
The encoder finds an exact color code only when the entered value can be represented as a 2 or 3 significant digit mantissa times an available multiplier (integer result with no fractional part). Standard resistor values from the E-series (E12, E24, E48, E96) are designed to be exactly representable in color bands, so they will always encode correctly. Arbitrary values like 1234 Ω may not have an exact 4-band code but will often work in 5-band mode.
Tips
- Hold the resistor so the gold or silver tolerance band is on the right — the remaining bands read left to right
- If unsure whether a resistor is 4-band or 5-band, try both modes and check which gives a standard E-series value
- Use 5-band mode for any precision resistor (tolerance ±1% or tighter)
- The color reference table at the bottom of the page lists digit, multiplier, tolerance, and TCR for all 13 colors