Inductor Color Code Calculator
An Inductor Color Code Calculator is a tool that decodes the colored bands on inductors to determine their inductance value and tolerance. Inductors are passive electronic components that store energy in magnetic fields and are essential in filters, power supplies, and signal processing circuits.
Small through-hole inductors use color bands because there's insufficient space to print numeric values. The color coding system is similar to resistors but with different units - microhenries (µH) instead of ohms (Ω).
Key concepts this calculator handles:
- Digit Bands: First two bands give significant digits
- Multiplier Band: Third band determines order of magnitude
- Tolerance Band: Fourth band indicates accuracy percentage
- Unit Conversion: Automatically converts between µH, mH, and H
Follow these simple steps to decode your inductor's color bands:
- Band 1 (1st Digit): First color from the end (typically brown, red, orange, etc.)
- Band 2 (2nd Digit): Second color value (0-9)
- Band 3 (Multiplier): Third color determines multiplication factor
- Band 4 (Tolerance): Fourth color indicates accuracy (±5%, ±10%, etc.)
The calculator instantly provides:
- Exact inductance value in microhenries (µH)
- Converted value in millihenries (mH) and henries (H)
- Tolerance percentage (accuracy range)
- Color code sequence for verification
Different colors represent different values in inductor color coding. Use this table as a reference:
| Color | Digit | Multiplier | Tolerance | Example |
|---|---|---|---|---|
| Black | 0 | ×1 µH | ±20% | 10 = 10µH |
| Brown | 1 | ×10 µH | ±1% | 11 = 110µH |
| Red | 2 | ×100 µH | ±2% | 12 = 1,200µH |
| Orange | 3 | ×1,000 µH | ±3% | 13 = 13,000µH |
| Yellow | 4 | ×10,000 µH | ±4% | 14 = 140,000µH |
| Gold | - | ×0.1 µH | ±5% | 10 = 1µH |
| Silver | - | ×0.01 µH | ±10% | 10 = 0.1µH |
Start reading from the band closest to one end. Typically, there's a wider gap before the tolerance band, or gold/silver bands are always at the tolerance end.
Below are answers to frequently asked questions about inductor color codes and decoding:
Finding the starting point is crucial for correct decoding. Look for these clues:
- Wider Gap: Look for a wider space between bands - tolerance band is usually isolated
- Gold/Silver Band: These colors usually appear only as tolerance (4th band)
- Closer to Lead: First band is typically closer to one of the component leads
- Manufacturer Mark: Some inductors have a dot or line near the first band
If still unsure, try reading both directions. The correct reading will yield a standard E-series value (like 10, 22, 47, 68, etc.).
Inductors come in both 4-band and 5-band configurations:
| 4-Band | 5-Band |
|---|---|
| Band 1: 1st Digit | Band 1: 1st Digit |
| Band 2: 2nd Digit | Band 2: 2nd Digit |
| Band 3: Multiplier | Band 3: 3rd Digit |
| Band 4: Tolerance | Band 4: Multiplier |
| - | Band 5: Tolerance |
5-band inductors provide an extra digit for more precision. Our calculator handles 4-band inductors, which are most common.
Common inductor values follow the E-series standard. Here are typical applications:
| Inductance | Color Code | Typical Application |
|---|---|---|
| 10 µH | Brown-Black-Black | RF circuits, filters |
| 100 µH | Brown-Black-Brown | Power supply input filters |
| 1 mH (1000 µH) | Brown-Black-Red | Audio filters, chokes |
| 10 mH | Brown-Black-Orange | Power line filtering |
| 100 mH | Brown-Black-Yellow | Transformers, relays |
Use the calculator above to decode your specific inductor value.
If color codes are faded or absent, use these measurement methods:
- LCR Meter: Most accurate method (professional)
- Oscilloscope Method: Create LC circuit, measure resonant frequency
- Multimeter with L Function: Some advanced meters measure inductance
- Bridge Method: Compare with known inductor value
- Online Calculator: Use our tool by estimating colors
If your decoded value isn't a standard value, check these common issues:
- Wrong Starting End: Try reading from opposite direction
- Color Confusion: Brown vs Red, Blue vs Violet in poor light
- Faded Colors: Old inductors may have discolored bands
- Non-Standard Coding: Some manufacturers use proprietary codes
- Damaged Component: Physical damage may affect color accuracy
Standard E-series values: 10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, 82, 100, etc.
Some small inductors use colored dots instead of bands. The decoding is identical:
- Dot 1: First digit (same as Band 1)
- Dot 2: Second digit (same as Band 2)
- Dot 3: Multiplier (same as Band 3)
- Dot 4: Tolerance (same as Band 4)
- Reading Order: Typically left to right or top to bottom
Use the same calculator inputs - just treat dots as color bands.