# Resistor Calculator (Color Code & SMD)

> Calculate resistance values interactively from 4, 5, and 6 band color codes, convert values back to color codes, or decode SMD markings (3-digit, 4-digit & EIA-96).

- Open in browser: https://pockettoolbox.org/en/resistor-calculator
- Runs entirely in your browser; files and input are never uploaded.

## How it works

Interactive 4-, 5-, and 6-band resistor calculator with visual color band preview and SMD code decoder.

Supports bidirectional conversion between color bands and resistance values, tolerance ranges (Min/Max Ohm), temperature coefficients (PPM), and SMD resistor decoding (e.g. 103, 4702, 01C).

Color code→value: lookup array [black=0, brown=1, ..., white=9] for value bands; multiplier map and tolerance map. Value = (d1*10+d2+d3*…) × multiplier. Value→color code: decomposition of the normalized value via division and modulo. SMD 3/4-digit: mantissa from first N-1 digits, exponent = last digit, value = mantissa × 10^exponent. EIA-96: lookup table with 96 values + letter multiplier map. E-series lookup: binary search in the precomputed E12/E24/E96 array for the nearest standard value.

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PocketToolbox (https://pockettoolbox.org/en)