Resistor Color Code Calculator
This resistor color code calculator decodes any 4-band resistor. Select the four colour bands from left to right and instantly read the resistance value, tolerance percentage, and the minimum and maximum resistance in the tolerance range.
Select band colours
Hold the resistor with the tolerance band (gold/silver) on the right. Select left to right.
Resistor colour code reference
| Colour | 1st/2nd digit | Multiplier | Tolerance |
|---|---|---|---|
| Black | 0 | ×1 | — |
| Brown | 1 | ×10 | ±1% |
| Red | 2 | ×100 | ±2% |
| Orange | 3 | ×1 kΩ | — |
| Yellow | 4 | ×10 kΩ | — |
| Green | 5 | ×100 kΩ | — |
| Blue | 6 | ×1 MΩ | — |
| Violet | 7 | ×10 MΩ | — |
| Grey | 8 | ×100 MΩ | — |
| White | 9 | ×1 GΩ | — |
| Gold | — | ×0.1 | ±5% |
| Silver | — | ×0.01 | ±10% |
Common Questions
Frequently asked questions
- How do I read a 4-band resistor color code?
- Hold the resistor so the tolerance band (usually gold or silver) is on the right. Read left to right: Band 1 (first significant digit), Band 2 (second significant digit), Band 3 (multiplier — the power of ten to multiply by), Band 4 (tolerance). For example, Brown-Black-Red-Gold = 1, 0, ×100, ±5% = 1000 Ω ±5% = 1 kΩ ±5%.
- What do the resistor color codes mean?
- Each colour maps to a digit: Black=0, Brown=1, Red=2, Orange=3, Yellow=4, Green=5, Blue=6, Violet=7, Grey=8, White=9. For the multiplier band, Gold=×0.1 and Silver=×0.01. The tolerance band uses: Brown=±1%, Red=±2%, Gold=±5%, Silver=±10%. A useful mnemonic for the digit order is: "BB ROY of Great Britain Values Gold Silver".
- What is a 5-band resistor?
- Precision resistors (1% and better) use 5 colour bands: Band 1, Band 2, and Band 3 are the first three significant digits; Band 4 is the multiplier; Band 5 is the tolerance. This allows finer resolution — for example, Red-Red-Black-Brown-Brown = 2, 2, 0, ×10, ±1% = 220 Ω ±1%. This calculator handles 4-band resistors; 5-band resistors follow the same colour-to-digit mapping.
- Why do standard resistor values follow the E-series?
- Standard resistor values are not arbitrary — they follow the E-series (E12, E24, E96, E192), which space values logarithmically so that the tolerance ranges of adjacent values just overlap. E12 gives 12 values per decade (20% tolerance), E24 gives 24 values (5% tolerance), and E96 gives 96 values (1% tolerance). This minimises the number of distinct values needed to cover any resistance you might need.
- What is a thermistor and does it have a color code?
- A thermistor is a resistor whose resistance changes significantly with temperature — NTC (negative temperature coefficient) types decrease with increasing temperature, PTC types increase. Thermistors do not use the standard colour-band coding; their value and B-parameter are printed as numbers on the body or listed in a datasheet.
- What tolerance should I choose for my project?
- ±5% (gold) resistors are adequate for most general-purpose analogue and digital circuits. ±1% (brown) resistors are used in precision voltage dividers, instrumentation amplifiers, and filter networks where accuracy matters. For audio, RF, or metrological work, ±0.1% or better is sometimes specified. Higher precision costs slightly more and is only worth it when the circuit performance actually depends on close matching.
- Can I use this calculator for SMD resistors?
- SMD (surface-mount device) resistors use a numeric code rather than colour bands. A 3-digit code like "103" means 10 × 10³ = 10 kΩ. A 4-digit code like "1002" means 100 × 10² = 10 kΩ in the EIA-96 variant. This calculator is for through-hole leaded resistors with colour bands; SMD codes follow a different decoding scheme.