
Resistor Color Code Calc +
Ohm's Law, LED & SMD Tool
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Free
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▶ Decode any resistor in seconds. Tap the color 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 color 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.
Color 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.
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What's New in Resistor Color Code Calc +
1.0
July 21, 2026


