First of all each color stands for a digit as follows.

• 0 Black.
• 1 Brown.
• 2 Red.
• 3 Orange.
• 4 Yellow.
• 5 Green.
• 6 Blue.
• 7 Violet.
• 8 Gray.
• 9 White.

The first two bands on the left, A and B, form a two digit number. The third band, C, tells you how many zeros to place after that number. This is the number of ohms.

For example

Yellow, Violet, Black.

Start by writing down the digits 47. Then put zero zeros after it. The resistor is a 47 ohm.

Blue, Red Brown.

Write down 62 and put 1 zero after it giving 620 ohms.

Orange, White, Yellow.

39 with 4 zeros after it is 390,000 ohms.

For resistors less than 10 ohms the gold and silver colors appear in the third, C, band. A gold third band means A.B is the number of ohms. A silver third band means 0.AB ohms.

For example

Green, Blue, Gold.

This is a 5.6 ohm resistor.

Red, Violet, Silver.

This is a 0.27 ohm resistor.

If you have studied the section on scientific notation at the end of the Basic DC Circuits page the resistor color code is AB x 10^C (A B times ten to the C). For this form gold is -1 and silver is -2.

Standard values.

• 10 +
• 11 *
• 12 +
• 13 *
• 15 +
• 16 *
• 18 +
• 20 *
• 22 +
• 24 *
• 27 +
• 30 *
• 33 +
• 36 *
• 39 +
• 43 *
• 47 +
• 51 *
• 56 +
• 62 *
• 68 +
• 75 *
• 82 +
• 91 *

+ Available in 5 or 10 percent.
* Available in 5 percent only.

The remaining decades repeat this one exactly. The list continues 100, 110, 120, 130, etc.

Why these funny numbers?

Four Band Codes.

Numerical coding

This code is also used on 1% or 0.1% resistors employing more digits. The last digit is the number of zeros that go after the first group of digits.

Antique Resistors.

Capacitor Color Codes.

There are two types of flat capacitors and one cylindrical that use color codes. They are shown in the figure below.

The designations A, B, and C, have the same meanings as in the resistor color code. The number of pico farads is AB with C zeros after it. Or in scientific notation AB x 10 (A B times ten to the C).

The 6 dot capacitor.

Dot 1, upper left, tells you something about the capacitor. A black dot means the capacitor is mica. A silver dot means it is military specification paper. I have some caps on which this dot is white. I don't know what this means. Dots 2, 3, and 4, give the capacitance in pico farads as explained above. Dot 5 gives the percent tolerance as follows.

• 1% Brown.
• 2% Red.
• 3% Orange.
• 4% Yellow.
• 5% Green.
• 6% Blue.
• 7% Violet.
• 8% Gray.
• 9% White.
• 5% Gold.
• 10% Silver.

Dot 6 gives the temperature coefficient of capacitance in parts per million per degree Centigrade. The color coding is as follows.

Three dot capacitors.

Tubular Capacitors.

The color code is read starting with the first band and is in pico farads. The fourth band gives the tolerance as follows.

The somewhat smaller ceramic types look as if the wire leads were wound around each end, as indeed they were, and come off the cap at right angles. These caps are often hollow and you can see right through them. The colors are not bands but small dots of paint that look as if they were painted on by hand. The first wide band may be a blob of paint which is larger than the rest.

Thanks to Mike McCarty from the Fun with Tubes email list I have information about the first color band or dot. This band gives the temperature coefficient in parts per million per degree centigrade. The code is as follows.

JAN = Joint Army Navy. A standard developed during WW II

Many newer capacitor types use the numeric code. It works the same as the color code but numbers replace the color bands or dots. Often there is a letter such as J or K after the number. Don't be fooled into thinking the number is supposed to be multiplied by 1000. Not so. The meaning of these letters is known only to the manufacturer and a few privileged high volume buyers that the maker has informed. God likely doesn't know either as I doubt if any of these very rich men ever talk to Him.