How to Use the Resistor Color Code Calculator
Resistors use colored bands instead of printed numbers to show their resistance value and tolerance — a global standard used on nearly every through-hole resistor. Read the colors in order and match them to their digits to get the resistance without a multimeter. This calculator supports both 4-band and 5-band resistors: just pick the color of each band and it instantly calculates the resistance and the tolerance range it can actually fall within.
Colors from black (0) through white (9) each represent a digit, and the multiplier band is the power of ten that digit gets multiplied by. For example, brown-black-red-gold on a 4-band resistor reads 10 × 100 = 1,000Ω (1kΩ) with ±5% tolerance. A 5-band resistor adds one more digit for a more precise reading.
When you're building a circuit or sorting through a parts bin, being able to read the value straight from the bands speeds things up a lot — especially useful when printed markings have worn off. Knowing the tolerance range also helps you judge whether a given resistor is precise enough for what your circuit needs.
Frequently Asked Questions
Read left to right so the tolerance band (usually gold or silver) ends up on the right. The first two bands (three on a 5-band resistor) are digits, followed by the multiplier and finally the tolerance.
A 4-band resistor has 2 digit bands plus a multiplier and tolerance, while a 5-band resistor has 3 digit bands for a more precise resistance value.
Tolerance shows how far the actual resistance can vary from the printed value, which matters for precision circuit design.