Resistor Calculator
Calculate resistor values, decode color codes and determine related electrical quantities.
Resistor basics
Color bands identify resistance and tolerance. Electrical quantities can also be related using Ohm's law.
Resistor Color Code
For a standard 4-band resistor, the first two bands are significant digits, the third is the multiplier and the fourth is tolerance. Five-band resistors use three significant digits.
Black = 0
Brown = 1
Red = 2
Orange = 3
Yellow = 4
Green = 5
Blue = 6
Violet = 7
Grey = 8
White = 9
Gold = ±5%
Silver = ±10%
How to Use the Resistor Calculator
1
Choose a Mode
Decode color bands, convert a resistance value to bands, or calculate an electrical quantity.
2
Enter the Values
Select the resistor bands or enter the relevant electrical values.
3
Calculate
The calculator displays the resistance, tolerance, color bands or electrical result.
Example
Brown–Black–Red–Gold
Brown = 1, Black = 0, Red = ×100, Gold = ±5%.
10 × 100 = 1,000 Ω = 1 kΩ ±5%
Frequently Asked Questions
The bands encode significant digits, a multiplier and tolerance. Four-band and five-band resistors use slightly different digit patterns.
Tolerance is the permitted variation between the marked resistance and the actual resistance.
Ohm's law relates voltage, current and resistance. It can be rearranged to find any one of these quantities when the other two are known.