Inductors can be labeled with a number of different ways. The most common are text codes and color codes.
Text Marking[]
- xRx values are in micro Henries (μH)
- Three digit values are in nano Henries (nH) or micro Henries (μH), depending on manufacturers choice
- First two digits are the value
- Third digit is the multiplier (or number of zeros added to the value)
- If there is an R, its acts as a decimal point, and there is no multiplier
- Examples:
- 472 = 47*102nH = 4700nH = 4.7μH (Coilcraft)
- 472 = 47*102μH = 4700μH = 4.7mH (Bourns)
- 4R7 = 4.7μH
- Suffix
- Sometimes the precision of the inductor will be marked, using a final letter F, G, J, K, or M
- F = +/-1%
- G = +/-2%
- J = +/-5%
- K = +/-10%
- M = +/-20%
- Sometimes the precision of the inductor will be marked, using a final letter F, G, J, K, or M
Color Code Markings[]
Inductors can be marked by colored bands or colored dots. Each color represents a value.
Band A | Band B | Band C | Band D |
---|---|---|---|
1st Digit | 2nd Digit | Multiplier | Tolerance |
1 | Silver 10-2 (0.01uH) | Gold 5% | |
Gold 10-1 (0.1uH) | Silver 10% | ||
Black 0 | Black 100 (1uH) | Black 20% | |
Brown 1 | Brown 1 | Brown 101 (10uH) | |
Red 2 | Red 2 | Red 102 (100uH) | |
Orange 3 | Orange 3 | Orange 103 (1000uH) | |
Yellow 4 | Yellow 4 | Yellow 104 (10000uH) | |
Green 5 | Green 5 | Yellow 104 (10000uH) | |
Blue 6 | Blue 6 | ||
Violet 7 | Violet 7 | ||
Gray 8 | Gray 8 | ||
White 9 | White 9 |
note: brown and violet can look very similar on some components. Violet and white can also look similar sometimes
Example 47 micro Henry
- Band colors:
- 1st band: yellow=4
- 2nd band: violet=7
- 3rd band: black=10^0=1
- Inductor value = 47x10^0uH = 47uH
- 4th band: silver = 10% tolerance
- inductance=47+-10
References[]
- Inductor color codes
- Transformer color codes
- Component codes
- Inductor history: includes color codes dot and striped