Inductor Color Code Calculator
Inductor Color Code Calculator
Read a four-band moulded inductor — two digits, a multiplier and a tolerance, in microhenries — or work the other way and find the bands for the value you want. Covers the EIA four-band scheme and the military marking with its wide silver body band and gold decimal point.
Inductor colour bands
Blue, grey, gold, silver (EIA four-band)
Reading the bands
military, no gold band: the same, after a double-width silver identifier band
military, gold in the second value band: L = digit1 . digit2 µH (1 to 9.9 µH)
military, gold in the first value band: L = 0 . digit1 digit2 µH (under 1 µH)
reactance: XL = 2πfL
- digit1, digit2
- black = 0 to white = 9, the same colours as the resistor code
- multiplier
- silver ×0.01, gold ×0.1, black ×1, brown ×10, red ×100, orange ×1,000
- tolerance
- gold ±5%, silver ±10% — the only two the source document gives
- silver body band
- double width, at one end: a military identifier, not a value
Worked example
Blue, grey, gold, silver (EIA four-band)
Blue = 6, grey = 8: the digits are 68
Gold multiplier = ×0.1, so 68 × 0.1 = 6.8 µH = 6.8 µH
Silver = ±10%, so the part is somewhere between 6.12 µH and 7.48 µH
The same value on a military part is marked differently: a double-width silver band, then blue, GOLD, grey — where the gold band is the decimal point, not a multiplier, giving 6.8 directly
At 10 MHz its reactance is 2πfL = 427.3 Ω
Read it from the end where the bands bunch up. If there is a wide silver band, that end is the start and the band is not part of the value
Inductor colour code (value in microhenries)
| Colour | Digit | Multiplier | Tolerance | Notes |
|---|---|---|---|---|
| Silver | — | ×0.01 | ±10% | double width: this is a MIL-marked part |
| Gold | decimal point (MIL, values under 10 µH) | ×0.1 | ±5% | — |
| Black | 0 | ×1 | — | — |
| Brown | 1 | ×10 | — | — |
| Red | 2 | ×100 | — | — |
| Orange | 3 | ×1,000 | — | — |
| Yellow | 4 | — | — | — |
| Green | 5 | — | — | — |
| Blue | 6 | — | — | — |
| Violet | 7 | — | — | — |
| Grey | 8 | — | — | — |
| White | 9 | — | — | — |
Colour bands for common inductor values
| Value | Bands with a ±5% tolerance | Bands with a ±10% tolerance |
|---|---|---|
| 100 nH | Brown, Black, Silver, Gold | Brown, Black, Silver, Silver |
| 220 nH | Red, Red, Silver, Gold | Red, Red, Silver, Silver |
| 470 nH | Yellow, Violet, Silver, Gold | Yellow, Violet, Silver, Silver |
| 1 µH | Brown, Black, Gold, Gold | Brown, Black, Gold, Silver |
| 2.2 µH | Red, Red, Gold, Gold | Red, Red, Gold, Silver |
| 4.7 µH | Yellow, Violet, Gold, Gold | Yellow, Violet, Gold, Silver |
| 6.8 µH | Blue, Grey, Gold, Gold | Blue, Grey, Gold, Silver |
| 10 µH | Brown, Black, Black, Gold | Brown, Black, Black, Silver |
| 22 µH | Red, Red, Black, Gold | Red, Red, Black, Silver |
| 47 µH | Yellow, Violet, Black, Gold | Yellow, Violet, Black, Silver |
| 100 µH | Brown, Black, Brown, Gold | Brown, Black, Brown, Silver |
| 220 µH | Red, Red, Brown, Gold | Red, Red, Brown, Silver |
| 470 µH | Yellow, Violet, Brown, Gold | Yellow, Violet, Brown, Silver |
| 1 mH | Brown, Black, Red, Gold | Brown, Black, Red, Silver |
| 4.7 mH | Yellow, Violet, Red, Gold | Yellow, Violet, Red, Silver |
| 10 mH | Brown, Black, Orange, Gold | Brown, Black, Orange, Silver |
Reading an inductor, and where this page stops
A moulded choke is a coil in an epoxy body the same shape and size as a resistor, and it is marked the same way — which is the problem, because the colours mean the same digits and the answer is in MICROHENRIES, not ohms. Blue, grey, gold, silver on a resistor is 6.8 Ω ±10%; on an inductor it is 6.8 µH ±10%. There is no way to tell the two apart by the bands alone. Inductors are usually a little fatter, often have squarer ends, and a measurement on a meter with an inductance range settles it immediately.
The four-band EIA scheme is the ordinary one: two digit bands, a multiplier band and a tolerance band, read from the end where the bands are bunched together. Digits run black 0 through white 9. Multipliers are the same colours again, from black ×1 up to orange ×1,000, with gold ×0.1 and silver ×0.01 for the sub-10 µH RF chokes that are most of what you will meet. Tolerance is gold ±5% or silver ±10%.
The military marking puts a double-width silver band at one end first. That band carries no value — it says only that the part was made to a military specification — and reading it as a multiplier is the classic mistake. What follows is three value bands and a tolerance band, and the three value bands have a twist: if one of the first two is gold, it is a DECIMAL POINT rather than a multiplier, and the other two bands are the digits. Gold in the second position gives values from 1 to 9.9 µH, so silver, blue, gold, grey, silver is 6.8 µH ±10%. Gold in the first position puts the point in front of both digits, for values below 1 µH. Above 10 µH there is no gold band and the three read as digit, digit, multiplier, exactly as in the EIA scheme — silver, red, violet, brown, gold is 270 µH ±5%.
Where this page stops, and why. Inductor marking is genuinely less standardised than resistor marking, and it is worth being blunt about it: there is no IEC standard at all. IEC 60062, which is what the resistor colour code and the capacitor code on this site rest on, is titled Marking codes for resistors and capacitors and its scope names only those two components. So this page follows a manufacturer’s published marking sheet — Bourns’, covering both schemes for its own choke families — checked colour for colour against a second, independent description. Where the two disagree, the page leaves the colour out rather than guessing. Three things are therefore NOT offered above: yellow as a ×10,000 multiplier, black or a missing band as ±20%, and the tighter tolerance colours (brown ±1%, red ±2%, green ±0.5% and the rest) that calculator sites copy across from the resistor code. The first two appear in one of the two sources and not the other; the third appears in neither. If your part carries one of them, trust its datasheet and not any colour chart, including this one.
Once you know the value. The colour code tells you the inductance and nothing else, and for an inductor that is less than half the story: the current at which the core saturates, the DC resistance, the Q and the self-resonant frequency are all missing, and above self-resonance the part behaves as a capacitor. The reactance figure above, 2πfL, is only valid well below that. For what the inductance does in a circuit, the reactance calculator and the LC resonant frequency calculator take it from here; to wind your own instead of buying one, see the air-core inductor calculator and the toroid turns calculator.
Frequently asked questions
How do you read an inductor colour code?
Two digit bands, then a multiplier band, then a tolerance band, read from the end where the bands are closest together. The answer is in microhenries. Blue, grey, gold, silver is 68 × 0.1 = 6.8 µH ±10%.
Is the inductor colour code the same as the resistor colour code?
The colours mean the same digits and the same powers of ten, but the unit is microhenries instead of ohms, the multiplier only runs from ×0.01 to ×1,000, and the only tolerance colours in the manufacturer’s sheet are gold ±5% and silver ±10%. There is also no IEC standard behind it — IEC 60062 covers resistors and capacitors only.
What does a wide silver band on an inductor mean?
It is the military identifier band, and it carries no value at all. It sits at the start, and the three bands after it are the inductance with the tolerance last. Reading it as a ×0.01 multiplier is the commonest error on these parts.
What does a gold band in the middle of an inductor mean?
On a military-marked part, a gold band in the first or second of the three value bands is a decimal point, used for values under 10 µH. Silver, blue, gold, grey, silver reads as 6.8 µH ±10%: the gold is the point, not a multiplier.
How do I tell an inductor from a resistor?
Not from the bands — they use the same colours. Moulded chokes tend to be slightly fatter with squarer ends, and an ohmmeter is decisive: a small choke reads a fraction of an ohm to a few ohms, where a resistor reads its marked value. A meter with an inductance range settles it outright.
Why does this page not list more tolerance colours?
Because they could not be sourced. The manufacturer’s marking sheet this page follows gives gold ±5% and silver ±10% and nothing else, and a second independent description agrees. The tighter tolerance colours that appear on many calculator sites are borrowed from the resistor code, and printing them here would be inventing a standard rather than reporting one.
Related calculators
References
- Bourns Inc. Color Code Marking (MIL STD), cylindrical choke coil marking sheet for the 9130, 9210, 9220, 9230, 9250, 9310 and 8250 (MIL) and 5300, 77F, 78F, 79F and 8230 (EIA) series. Gives both schemes: the EIA four-band code (digit, digit, multiplier, tolerance, in µH) and the military code with a double-width silver identifier band, three value bands and a tolerance band, including the rule that “when either the first or second band of the three bands is gold, this band shall represent the decimal point for inductance values less than 10”. Its worked examples, 6.8 µH ±10% and 270 µH ±5%, are reproduced by this page and asserted in its test suite.
- IEC 60062:2016. Marking codes for resistors and capacitors, scope: “specifies designation and marking codes for capacitors and resistors”. Cited here for what it does NOT cover — there is no IEC colour code for inductors, which is why this page rests on a manufacturer document instead.
- learnabout-electronics.org, Inductors and Inductance — inductor colour codes. An independent second description of both schemes, used to corroborate every colour offered above. It additionally lists yellow as a ×10,000 multiplier and black (or no band) as ±20%; those appear in no manufacturer document that could be found, so they are deliberately not offered on this page.
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