A Beginner’s Guide to Reading Resistor Values
Thursday, February 5th, 2009Resistors have specific values which are indicated using a series of colored stripes on the body of the resistor. Each color is assigned a value, and each stripe position determines its purpose. It takes some practice to learn how to read the values quickly, but here is a guide you can use to help you.
Begin by holding the resistor so that the multiple colored rings are at the top of the body. The picture below is one example.
The first stripe is the first number in the value of the resistor.
The second stripe indicates the second number of the resistor value.
For example, in the picture below, the first stripe is orange, which equals 3 and the second stripe is black which equals 0. So the complete number is 30.
The third stripe color indicates the number of zeros that follows the first two. In the case of the pictured resistor, that value is 0, so no additional zeroes will follow the 30.
This means that this resistor has a value of 30 ohms.
The last stripe, which is usually separated from the others,
indicates the tolerance. In our picture, the resistor has a tolerance of 5%.
30 Ohm Resistor
Stripe Color0 = Black 1 = Brown 2 = Red 3 = Orange 4 = Yellow 5 = Green 6 = Blue 7 = Violet 8 = Gray 9 = White |
Tolerance1% = Brown 2% = Red 3% = Orange 4% = Yellow 5% = Gold 10% = Silver 20% = None |
The Gold or Silver band should always be to the right as you read from left to right. If there is no tolerance band, the side with a band closest to a lead is the first band.
If you cannot distinguish the colors of the bands on a resistor, the only way to read it is by using a multi-meter across the leads.
Do you have any special tricks you use to help you read resistor values? Please feel free to share.
