🔌 Resistor Calculator
Those tiny colored bands are the resistor's datasheet: the first two bands are digits, the third is the multiplier and the fourth is the tolerance. Select the four colors and the calculator reads the value for you.
Results are shown in ohms, kilo-ohms or mega-ohms with the tolerance range, so you can check parts before soldering them in.
How to use this calculator
Select the four band colors on the resistor: the two digit bands, the multiplier band and the tolerance band. The calculator reads out the resistance in ohms, kilo-ohms or mega-ohms.
- Pick Band 1, the first digit color.
- Pick Band 2, the second digit color.
- Pick Band 3, the multiplier color.
- Pick Band 4, the tolerance color, then read the resistance.
Frequently asked questions
What does the Resistor Calculator compute?
It decodes a 4-band resistor color code. The first two bands give two digits, the third band multiplies them, and the fourth gives the tolerance. The result is shown in ohms, kilo-ohms or mega-ohms with the tolerance percentage.
How do the bands work?
Each color stands for a digit from 0 (black) to 9 (white). The multiplier band scales the two-digit number: red means times 100, orange times 1K, gold times 0.1. The tolerance band, often gold or silver, gives the accuracy range.
Can you give a worked example?
Yellow, violet, red, gold is 47 times 100, which is 4.7 kilo-ohms with plus or minus 5 percent tolerance.
What about 5-band resistors?
This tool covers the common 4-band type. Five-band resistors add a third digit band for precision values and are not decoded here.