Inductor color code calculator — µH decoder
Decode the color bands on an inductor into its inductance in microhenries — the older radial/axial style marked with 3 (or 4) bands.
Bands
Decoded value
Inductance
10 ×100 = 1000 µH
Tolerance
Color → %
Worked example: brown-black-red-gold = 10 × 100 = 1000 µH = 1 mH ±5%.
Quick reference
| Value | Bands | Tolerance |
|---|---|---|
| 2.2 µH | Red 2 · Red 2 · ×0.1 | Gold ±5% |
| 4.7 µH | Yellow 4 · Violet 7 · ×0.1 | Gold ±5% |
| 10 µH | Brown 1 · Black 0 · ×1 | Gold ±5% |
| 22 µH | Red 2 · Red 2 · ×1 | Gold ±5% |
| 47 µH | Yellow 4 · Violet 7 · ×1 | Gold ±5% |
| 100 µH | Brown 1 · Black 0 · ×10 | Gold ±5% |
| 220 µH | Red 2 · Red 2 · ×10 | Gold ±5% |
| 470 µH | Yellow 4 · Violet 7 · ×10 | Gold ±5% |
| 1 mH | Brown 1 · Black 0 · ×100 | Gold ±5% |
About the model
Military-style radial and axial inductors (MIL-PRF-15305) use the same color code as resistors, but the decoded value is in microhenries: the first two rings are significant digits, the third is the decimal multiplier in µH (silver ×0.01 and gold ×0.1 for sub-µH parts), and an optional fourth ring gives the tolerance. The value is (d1×10 + d2) × multiplier µH.
Modern surface-mount (SMD) inductors use a numeric code instead of bands — for example 4R7 = 4.7 µH, with a multiplier letter like R (×0.1) or n (×0.001).
Browse related parts:
Frequently asked questions
How is the inductance value calculated from the color bands?
The first two bands are the significant digits and the third is the decimal multiplier, so the value is (d1×10 + d2) × multiplier in microhenries. For example brown-black-red = 10 × 100 = 1000 µH, which the tool displays as 1 mH — values of 1000 µH and above auto-convert to mH.
What does a gold or silver multiplier band mean on an inductor?
A gold multiplier band is ×0.1 and a silver one is ×0.01, which is how sub-microhenry parts are coded — brown-black-gold decodes to 1.0 µH. On these military-style (MIL-PRF-15305) axial and radial inductors the third band is a power-of-ten multiplier just like a resistor, but the decoded result is in µH rather than ohms.
What tolerance does each inductor tolerance band represent?
The optional fourth band carries the tolerance: silver is ±10%, gold is ±5% and brown is ±1%. Gold (±5%) is the default and covers most parts — for example brown-black-red-gold is 10 × 100 = 1000 µH, or 1 mH ±5%.
Band colors can be hard to tell apart under poor lighting — when in doubt, confirm with an LCR meter. ICBOMS provides this tool for reference only.