calc.engineer / PCB & Electronics / Resistor Color Code

Resistor Color Code v1.0.0

Decodes 4-band or 5-band resistor color codes into resistance value, tolerance, and min/max range. Accepts an ordered array of color names (left-to-right as printed on the resistor body). Supports standard EIA color codes including gold and silver multiplier/tolerance bands. Outputs the nominal resistance in ohms, a human-readable formatted value (e.g. '4.7kΩ'), tolerance percentage, and the min/max resistance range. Chain into ohms_law or led_resistor for circuit analysis.

feeds ohms_law →feeds led_resistor →
Array of 4 or 5 color band names from left to right. 4-band: [digit1, digit2, multiplier, tolerance]. 5-band: [digit1, digit2, digit3, multiplier, tolerance].
Fill in the inputs and Compute to see the structured result.

From an agent (MCP) or the API

curl -X POST https://calc.engineer/api/resistor_color_code \
  -H "Content-Type: application/json" \
  -d '{"bands": …}'

MCP: connect to https://calc.engineer/mcp and call resistor_color_code.

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