Resistor Colour Code Calc

Tap the colour bands and read the resistance instantly, or enter a value to get the bands. Plus Ohm's law, LED resistor and SMD code tools.

▶ Decode any resistor in seconds. Tap the colour bands on a big, clear resistor graphic and the value, tolerance and temperature coefficient update live — 4, 5 or 6 bands, with the nearest E24 or E96 standard shown too.

▶ Go the other way. Type a value like 4.7k and the app snaps it to the nearest standard part and paints the colour bands back onto the resistor, with the error against your input.

▶ Everyday electronics math in one place. Ohm's law solves V, I, R or P from any two; the LED resistor tool sizes a series resistor from supply voltage, LED forward voltage and current.

▶ Read SMD codes fast. Enter a 3-digit, 4-digit, R-notation or EIA-96 code and get the value, plus series and parallel resistance helpers for quick combinations.

▶ Works fully offline with a clean history of your calculations. Share a result, switch languages, no account needed.

Colour names and values follow the standard IEC bands; always double-check critical parts against the printed markings and a meter. This is a reference and learning tool, not a substitute for measuring your actual components.