Developer tools / Electronics

Resistor color code calculator.

Decode 4-band and 5-band through-hole resistors. Select band colors to see the visual resistor update in real time and calculate the nominal resistance and tolerance range.

Use the calculator

Free online tool

Decode resistor bands

Select your band count, then choose the colors starting from the left.

Worked examples from tutorial

Calculated resistance

Nominal resistance
27 kΩ
Tolerance percentage
±5%
Allowable variation
±1.35 kΩ
Specified resistance range
25.65 kΩ to 28.35 kΩ

Calculations run locally in your browser. Values are not sent to TeachyLeaf. Color band conventions follow standard IEC 60062 / EIA-RS-279 guidelines. Nominal values represent manufacturer ratings under standard laboratory conditions, not measured values of an individual physical component.

Learn the reading conventions and band tables in How to read resistor color codes. See how resistor values determine output voltage in the Voltage divider lesson, or simplify a loaded resistor network with the Thevenin equivalent calculator.