Reference · Components 3.x
🏁 Resistor Tools
Two practical bench tools: a reverse color-code calculator that turns a resistance value into its colored bands, and an E-series finder that snaps any value to the nearest real, purchasable standard resistor. A perfect companion to the Color Code Quiz.
Resistance Value → Color Bands
Type a resistance and choose the unit. The tool shows the standard 4-band and 5-band color codes and draws the resistor so you can match it on the bench.
4-band vs 5-band: 4-band resistors use 2 significant digits + multiplier + tolerance. 5-band (precision) resistors use 3 significant digits + multiplier + tolerance, so they can represent values like 4.99 kΩ that a 4-band code cannot.
Standard (E-Series) Value Finder
Resistors only come in fixed "preferred values" set by the E-series. Enter any target value and this finds the closest real resistor you can actually buy, in each common series.
Why E-series? The values are spaced so that with a given tolerance, the ranges of adjacent values just touch — covering every possible resistance with the fewest distinct parts. E6 = 20% tolerance, E12 = 10%, E24 = 5%, E96 = 1%.