Select each color band to decode a resistor's value, tolerance, and range from its color code.

How to Use the Resistor Calculator

Toggle between 4-Band and 5-Band first, since that determines how many digit bands you'll set. Pick a color for each digit band, then the multiplier band, then the tolerance band — resistance, tolerance, and the min/max range all update as soon as you change any dropdown.

A 4-band resistor gives you two significant digits before the multiplier kicks in; a 5-band gives you three. That extra digit isn't decoration — it's precision. A 4-band resistor reading "47 × 100" could be anywhere from 4465 to 4935 ohms at 5% tolerance, but manufacturers making tighter-tolerance parts (1% and below) need a way to specify a third significant figure, so they add a band rather than trying to cram more precision into a system built for two digits.

4-Band: Resistance = (Digit 1 × 10 + Digit 2) × Multiplier
5-Band: Resistance = (Digit 1 × 100 + Digit 2 × 10 + Digit 3) × Multiplier

The genuinely confusing part of reading resistor colors, even for people who've done it for years: gold and silver mean completely different things depending on which band they're sitting in. As a multiplier, gold means ×0.1 and silver means ×0.01, pushing the value down into fractional ohms. As a tolerance band, the same two colors mean ±5% and ±10% respectively — nothing to do with magnitude at all. There's no shortcut here; you just have to know which band you're looking at.

Resistance auto-scales to whatever unit reads cleanest — 470 ohms stays as "470 Ω," but 4,700 ohms displays as "4.7 kΩ" and anything past a million shows in megaohms. The range shown underneath applies the tolerance percentage to the nominal value in both directions, which is the number that actually matters when a resistor's measured value needs to fall within spec.