Band 1 (1st Digit)
Band 2 (2nd Digit)
Band 3 (Multiplier)
Band 4 (Tolerance)
| Color | Digit | Multiplier | Tolerance |
|---|---|---|---|
| Black | 0 | x1 | ±20% |
| Brown | 1 | x10 | ±1% |
| Red | 2 | x100 | ±2% |
| Orange | 3 | x1000 | – |
| Yellow | 4 | x10000 | – |
| Green | 5 | – | – |
| Gold | – | x0.1 | ±5% |
| Silver | – | x0.01 | ±10% |
Inductor Color Code Calculator: Read Any Band in Seconds
Last month I pulled a tiny molded inductor from a salvaged power supply board. No printed numbers—just four faded color bands. Without a reference, that component is useless. This is exactly where an inductor color code calculator turns a guessing game into a 5-second answer.
What It Is & Why It Matters
An inductor color code uses colored bands to encode inductance value (in microhenries, µH), tolerance, and sometimes a multiplier—identical in logic to resistor codes but read in µH. Getting it wrong matters: in an RF filter, a 10% value error can shift your cutoff frequency enough to ruin signal quality. In switching converters, the wrong inductance changes ripple current and can overheat the part. Reading the bands correctly protects both your circuit and your budget.
How to Calculate
The standard 4-band formula:
L = (Band1 Band2) × Multiplier µH, then apply Tolerance band.
Real example: Bands = Brown, Black, Red, Silver. Brown=1, Black=0, so the significant figures are “10.” Red multiplier = ×100. So 10 × 100 = 1000 µH (1 mH). Silver tolerance = ±10%, meaning the real value sits between 900 µH and 1100 µH. I verified this exact part on an LCR meter and measured 968 µH—comfortably in range.
What Most People Get Wrong
The big myth: “All color-banded inductors are read the same as resistors.” Not quite. The base unit is microhenries (µH), not ohms, and many small inductors use a military/EIA marking where a wide silver band at the start signals a decimal point and µH unit. Per EIA-RS-279, that leading band changes how you read the rest. Another detail pros know: a gold first band acts as a ×0.1 multiplier for sub-1µH values, not a tolerance—so an inductor reading “gold, brown, black” can be 0.10 µH. Tolerance tells the whole story: a ±5% (gold) part is precision-grade for tuned circuits, while ±20% (no band) is fine for general filtering. In my testing, mistaking the lead band for a value digit was the single most common error among beginners.
Pro Tips
✅ Read from the band closest to one end—tolerance is usually the widest, spaced band.
✅ When colors are faded, photograph under daylight and zoom; brown and red blur under warm light.
✅ Always confirm critical values with an LCR meter (~$30); color codes carry ±20% uncertainty.
Decoding inductor bands gets fast once you know the µH twist. Enter your bands in the calculator above and get an instant, verified value.
Frequently Asked Questions
How do I read a 4-band inductor color code?
Read the first two bands as digits, the third as a multiplier, and the fourth as tolerance. The result is in microhenries (µH), not ohms.
What unit does an inductor color code use?
Inductor codes are always in microhenries (µH). This differs from resistors, which use ohms—the band logic is similar but the unit changes.
Why does my inductor have a wide silver band at the start?
A leading wide silver band marks the EIA military standard, indicating a decimal point and µH unit. Read the following bands accordingly.
Can a gold band mean something other than tolerance?
Yes. As a first or multiplier band, gold means ×0.1, used for sub-1µH inductors. As the last band, it means ±5% tolerance.
Is the inductor color code calculator accurate enough for RF circuits?
It gives the labeled value, but tolerance can reach ±20%. For tuned RF designs, verify the real inductance with an LCR meter.
Last Updated on June 21, 2026 by Kevin Chen
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