Decode 3-band, 4-band and 5-band inductor color codes, calculate inductance in µH, mH or H, check tolerance range, and reverse lookup color bands from a value.
🧠 Key Insight: Inductor color bands use the same digit colors as resistors, but the result is in microhenries (µH). 3-band inductors show value only; 4-band and 5-band parts include a tolerance band, usually Gold or Silver, read last.
Common mistake: Do not read an inductor value as ohms. The color code may look like a resistor, but the calculated unit is normally µH. For replacement work, also confirm current rating, saturation current and whether a tolerance band is actually marked.
Enter an inductance value to find its color bands (nearest standard value shown).
Result
📊 Inductor Color Code Reference Table
Color
Digit
Multiplier (µH)
Tolerance
Temp. Coeff.
📋 Quick Inductor Reference
Common Values
RF / signal1µH–47µH
General filters100µH–1mH
Power chokes10µH–10mH
Tolerance Bands
Gold±5%
Silver±10%
Brown±1%
Reading Direction
Start sideDigits
Middle bandMultiplier
Last bandTolerance
📚 Engineering Notes
Inductance is only one ratingThe color code gives the nominal inductance, but current rating, saturation current, DCR and Q factor also matter in real circuits.
Measure when accuracy mattersOld axial inductors can have faded bands or manufacturer-specific markings. Use an LCR meter for repair or filter tuning work.
Power circuits need saturation checksA 100µH inductor may look correct by color code but still fail in a DC-DC converter if its saturation current is too low.
SMD inductors use different markingsMany SMD inductors use numeric codes like 100, 101 or 4R7 instead of color bands.
How to Read Inductor Color Codes
Like resistors, many axial and molded inductors use color bands to indicate their inductance value, tolerance, and sometimes temperature coefficient. While the color-to-digit mapping is the same, the multiplier result gives inductance in microhenries (µH) rather than ohms.
3-Band Inductors
A 3-band inductor uses band 1 and band 2 as significant digits, and band 3 as the multiplier in µH. It does not show a tolerance band, so the tolerance should be treated as not marked unless the datasheet or manufacturer information confirms it. Example: Brown–Black–Red = 1, 0, ×100 = 1000 µH (1 mH).
4-Band Inductors
The most common format. Bands 1 and 2 are significant digits, band 3 is the multiplier (power of 10 in µH), and band 4 is the tolerance. For example: Brown–Black–Red–Gold = 1, 0, ×100, ±5% = 1000 µH (1 mH) ±5%.
5-Band Inductors
Used for higher-precision inductors. Bands 1, 2, and 3 are three significant digits, band 4 is the multiplier, and band 5 is the tolerance. This allows more precise values to be encoded. Example: Brown–Black–Black–Brown–Brown = 1, 0, 0, ×10, ±1% = 1000 µH ±1%.
Inductor Color Code Examples
Use these examples to confirm the reading direction and the final unit before replacing a component in a circuit.
Bands
Calculation
Result
Typical use
Brown–Black–Red
10 × 100 µH
1 mH, tolerance not marked
3-band value-only marking
Brown–Black–Brown–Gold
10 × 10 µH
100 µH ±5%
Small filters, timing and signal circuits
Yellow–Violet–Red–Silver
47 × 100 µH
4.7 mH ±10%
General filtering or choke applications
Brown–Black–Black–Brown–Brown
100 × 10 µH
1 mH ±1%
Higher precision filter work
How Inductor Color Codes Differ from Resistor Color Codes
The color-to-number mapping is identical, but the unit changes. For resistors, the multiplier produces ohms (Ω). For inductors, the multiplier produces microhenries (µH). The tolerance band colors are the same. One practical difference: inductor color coding is less standardized across manufacturers — always verify against the datasheet when tolerance or exact value matters.
Additionally, some older inductor markings use a silver band to indicate an inductance value in the mH range, or position a silver first band to indicate a multiplier of 0.01. Always check orientation carefully: the body of the component and any manufacturer markings can help determine which end to read from.
Axial vs. Molded Inductors
Axial inductors have leads extending from each end, like resistors. The color bands wrap around the cylindrical body and are read from left to right, with the tolerance band (often gold or silver) closer to one end. These are common in through-hole RF and power circuits.
Molded inductors are encapsulated in a solid epoxy or phenolic body, making them more robust and moisture-resistant. They use the same color band system. Molded inductors are common in filter circuits, chokes, and RF applications. Their compact form factor and durability made them standard in consumer electronics through the 1990s and 2000s.
Tolerance Band Reference
If only three color bands are present, the tolerance is not marked on the component. In that case, use the datasheet or measure the part when exact inductance matters.
Silver — ±10%
Gold — ±5%
Brown — ±1%
Red — ±2%
Green — ±0.5%
Blue — ±0.25%
Violet — ±0.1%
Grey — ±0.05%
Reading Tips
For 4-band and 5-band inductors, the tolerance band (often gold/silver) is read last — orient the component accordingly.
If the first band appears to be gold or silver on a tolerance-marked inductor, you're probably reading from the wrong end.
For surface-mount inductors, inductance is usually printed directly in numeric codes (e.g., "101" = 100 µH, "4R7" = 4.7 µH). For similar marking styles, see the SMD Resistor Code Calculator and Capacitor Code Chart.
When in doubt, measure with an LCR meter to verify — inductor markings can fade or be ambiguous.
Temperature coefficient (TC) affects how inductance changes with temperature — important in precision oscillator and filter designs.
Common Inductor Values
Typical axial inductor values range from sub-µH RF chokes all the way to 100 mH or more for power filtering. Common standard values include 1 µH, 10 µH, 47 µH, 100 µH, 470 µH, 1 mH, 10 mH, and 100 mH. As with resistors, inductors are available in standard E-series values. The E12 and E24 series are most prevalent for inductors. After decoding a value, you can use the Reactance Calculator, LC Resonance Calculator, or Inductor Series/Parallel Calculator for circuit design checks.
❓ Frequently Asked Questions
The color digits are the same, but the unit is different. Resistor bands calculate ohms, while inductor color bands usually calculate microhenries (µH).
Read from the side opposite the tolerance band. Gold or silver is usually the tolerance band and should be read last.
A 3-band inductor usually uses two significant digits and one multiplier band. It gives the inductance value only; tolerance is not marked, so check the datasheet or measure with an LCR meter when accuracy matters.
A 4-band inductor usually uses two significant digits, one multiplier band, and one tolerance band.
A 5-band inductor usually uses three significant digits, one multiplier band, and one tolerance band for better precision.
Not directly. Many SMD inductors use printed numeric markings such as 101 or 4R7 instead of color bands.
Inductor markings can fade, and inductance can vary with frequency, current and tolerance. An LCR meter gives a more reliable result for repair and tuning work.
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