4 Band Resistor Color Code Calculator

The 4 band Resistor color code calculator is used to calculate the resistance of 4 band color coded resistors. Select the bands to find the resistance value.

The values of resistance and the wattage rating of large power resistors are imprinted on their bodies. The resistance of small carbon and metal film resistors is not labeled on their bodies. Instead, various colored bands are carved radially on the bodies of carbon resistors. One can read the color bands to find the value of resistors. A color-coded resistor might contain 4, 5, or 6 bands. While 4 Band resistors are the most popular type of colored resistors they are widely employed in electronics, hobbyists, and school projects.

How to Read a 4 Band Resistor

The first band from the left represents the first significant figure (digit) of resistance. The second band represents the second significant digit of resistance. The third band is the multiplier. The fourth band represents the tolerance value to which a resistance can vary. The fourth band is usually silver or golden in color.

As mentioned previously the most important rule which should be followed for reading the resistors is to start from the first band (which is on the left side). There are two ways to identify the first band from the left side.

  1. The first band is comparatively carved closer to the leg as compared to fourth.
  2. The fourth band is unique since it is silver or golden, Both these colors are not used in the first band.

The 4 band chart for calculating resistance is shown below:

4-band-resistor-color-code-chartAn illustration of 4 Band Resistor Color Coding

Let’s consider a resistor with whose bands from the left side is Brown, Black, Red, Gold.

4-band-1-k-resistor-brown-black-red-gold

Brown color indicates that first significant digit is 1, whereas black indicates the second significant digit is 0. Red color indicates a multiplier of 100 Ω and the rightmost golden band indicates a tolerance of 5%. So, a Brown, Black, Red, Gold colored resistor is decoded as 10*100Ω ±5% or 1 kΩ ± 5%.

The list of most commonly used resistors and their bands are indicated below:

Resistance 1st band 2nd Band 3rd band 4th Band
100 Ω ±5% Brown Black Brown Gold
470 Ω ±5% Yellow Violet Brown Gold
1 kΩ ±5% Brown Black Red Gold
2.2 kΩ ±5% Red Red Red Gold
10 kΩ ±5% Brown Black Orange Gold
22 kΩ ±10% Red Red Orange Silver
1 MΩ ±5% Brown Black Green Gold

Example problems

Example # 1: A 12 V battery connects to a resistor whose beads are Yellow, Violet, Brown, and Gold. Calculate the expected current which flows through the circuit.

Solution: The resistor is decoded to be 470 ohms. From Ohm’s law, we calculate the current:

I = V/R = 12 V / 470 Ω = 25.53 Amps

 

Example # 2: A Brown, Black, Green, Gold bead resistor connects to a relay which requires 10 mA actuating current. A 10 V source connects to the circuit. Comment the status of the relay.

Solution: From the bands, the resistance is read as 1 MΩ. In this condition the current flowing through the circuit is:

I = V/R = 10 V/1 MΩ = 10 µA

The relay requires 10 mA current for operation. In present case the current through circuit is too lower. Hence the relay will not operate.

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