Inductor colour code calculator

When you need this

The colour bands on an inductor are read just like those on a resistor: two digits, a multiplier, a tolerance. The differences are the units and the five-band military variant.

The bands in the drawing are the ones chosen in the form

How many bands on the body	3 bands4 bands5 bands (military: the first band is a double-width silver one)
First band — tens	blackbrownredorangeyellowgreenbluevioletgreywhite
Second band — units	blackbrownredorangeyellowgreenbluevioletgreywhite
Third band — multiplier	blackbrownredorangeyellowgoldsilver
Fourth band — tolerance	brownredorangeyellowgoldsilverblack
Result
Value
💡 How not to get the direction backwards The bands are read from the end of the body they are grouped towards. If you cannot tell which way round it goes, logic helps: the tolerance band is always gold or silver, and those colours never stand for the first digit — except in the military scheme, where gold means a decimal point. The value of an inductor is always in microhenries — unlike resistors, where the base unit is the ohm. Manufacturers do not always keep to the inductor colour code: if in doubt, measure.

📐 Formulas

Digits (the first two bands): black 0, brown 1, red 2, orange 3, yellow 4, green 5, blue 6, violet 7, grey 8, white 9.

Multiplier (the third band): black ×1, brown ×10, red ×100, orange ×1000, yellow ×10000, gold ×0.1, silver ×0.01.

Tolerance (the fourth band): brown ±1 %, red ±2 %, orange ±3 %, yellow ±4 %, gold ±5 %, silver ±10 %, black or no band at all ±20 %.

Three marking schemes:

• 3 bands — two digits and a multiplier; there is no tolerance band, so ±20 %.
• 4 bands — two digits, a multiplier, a tolerance.
• 5 bands (military) — the first band is always silver and double width, and only marks the standard itself. The other four are the same as before. The peculiarity: the digit bands may be gold, which stands for a decimal point:

gold in the first digit band:   L = 0.1·(second band) + 0.01·(third band)
gold in the second digit band:  L = (first band) + 0.1·(third band)

This is how inductors below 10 µH are marked, where the ordinary ×0.1 multiplier does not give enough resolution.

Notation:

• L — the value, always in microhenries — unlike resistors, where the base unit is the ohm
• from 1000 µH upwards the calculator shows millihenries

Limits of the calculator:

• The bands are read from the end of the body they are grouped towards
• Manufacturers do not always keep to the inductor colour code — if in doubt, measure
• In the military scheme gold in a digit band means a decimal point, not a multiplier

🎯 Where it is used

• Going through the parts box, where there are markings but no datasheet.
• Checking yourself before putting an inductor into a circuit.
• Reading military markings, which turn up in special-purpose equipment.

Practical notes:

1. If it is unclear which end to read from, logic helps: the tolerance band is always gold or silver, and those colours never stand for the first digit — except in the military scheme.
2. The drawing above shows exactly the bands chosen in the form: handy for comparing with the part in your hand.
3. Brown and red are easy to confuse on old parts. If the value looks odd for this circuit, check those two bands first.

© 2026 UR3PKI · CyberDev.Space · Content licensed under CC BY-NC-SA 4.0.

How to cite this calculator

UR3PKI. «Inductor colour code calculator». CyberDev.Space. https://cyberdev.space/en/radio/calculators/coils/color_code (licence CC BY-NC-SA 4.0).

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