🌈 Resistor Color Code Calculator
Select the color of each band on a standard 4-band resistor to find its resistance value and tolerance.
How resistor color codes work
Most through-hole resistors use colored bands instead of printed numbers to show their resistance value, because the bands can be read from any angle. A standard 4-band resistor uses the first two bands as significant digits, the third band as a multiplier, and the fourth band as the tolerance.
The formula
The resistance is calculated as (first digit × 10 + second digit) × multiplier. The tolerance band then tells you the acceptable range around that value — for example, a 5% tolerance on a 1,000 ohm resistor means the actual resistance could reasonably fall anywhere between 950 and 1,050 ohms.
Select the color of each band above to see the calculated resistance, its unit-friendly form (ohms, kilohms, or megohms), and the full tolerance range. This tool is for general reference; always verify critical values with a multimeter.