Inductor (Coil) Color Code Calculator (Colors → Inductance & Inductance → Colors)
Calculate the inductance and tolerance of a small inductor (coil) from its 3 or 4 color bands, shown in µH, mH, and H. You can also enter an inductance value to look up the matching color bands.
Color band reference table
| Color | Digit | Multiplier (µH) | Tolerance |
|---|---|---|---|
| Black | 0 | ×1 | — |
| Brown | 1 | ×10 | ±1% |
| Red | 2 | ×100 | ±2% |
| Orange | 3 | ×1,000 | ±3% |
| Yellow | 4 | ×10,000 | ±4% |
| Green | 5 | ×100,000 | — |
| Blue | 6 | ×1,000,000 | — |
| Violet | 7 | ×10,000,000 | — |
| Gray | 8 | ×100,000,000 | — |
| White | 9 | ×1,000,000,000 | — |
| Gold | — | ×0.1 | ±5% |
| Silver | — | ×0.01 | ±10% |
| No band (unmarked) | — | — | ±20% |
Tips
- Inductor color codes reuse the same digit and multiplier colors as resistors, but the unit is µH (microhenries), not Ω. Brown-black-red-gold reads as 1kΩ on a resistor, but as 1000µH (1mH) on an inductor.
- A 3-band inductor omits the tolerance band, which is treated as ±20% by convention. If a 4th band is present, select its color to see the exact tolerance.
- The tolerance band color-to-percent mapping differs from resistors: orange=±3%, yellow=±4%, and black=±20% are specific to inductors, so reusing the resistor tolerance table will give the wrong answer.
- If the "Inductance → Colors" mode finds no match, the value you entered likely does not round cleanly to 2 significant figures. Try rounding to the nearest standard value.
- RF chokes and power-line noise-suppression inductors are often marked with small values (a few µH to a few hundred µH), so entering the value in µH first tends to be the easiest to read.
Frequently asked questions
Side Note — Why coils borrow the same color language as resistors
Small inductors (coils) are often built as cylindrical parts that look a lot like resistors, and they face the same tight constraints on printing space. As a result, the "represent digits with color" scheme established for resistors was carried over directly, reusing the same sequence from black=0 through white=9. The physical quantity being represented is different, though — µH (inductance) rather than Ω (resistance) — so a reader who does not recognize that a part is a coil rather than a resistor can easily misread the value by orders of magnitude.
The subtly different tolerance-band color mapping has also long been a source of confusion for practitioners. Resistors use high-precision colors such as green=±0.5%, blue=±0.25%, and violet=±0.1%, while inductors commonly use orange=±3%, yellow=±4%, and black=±20% — assignments that do not appear on the resistor chart at all. This stems from resistors and inductors being standardized somewhat independently by industry groups over time, rather than from a single unified international standard; several references describe broadly similar but not identical conventions.
Small inductors quietly do a lot of work in places that are easy to overlook — RF tuning and filtering circuits, and choke coils used to suppress noise on power lines, to name two common examples. On a crowded board they can be hard to spot among capacitors and resistors, and in field work where direct measurement or datasheet lookup is not practical, reading the color bands is sometimes the only clue available. This tool is meant to sit alongside the resistor color code calculator and the capacitor code converter in the same electricity subcategory, together covering the common task of reading markings on passive components.