{
    "name": "Resistor Calculator",
    "url": "https://calculators.geekmidst.com/calculators/resistor-calculator",
    "markdown": "https://calculators.geekmidst.com/calculators/resistor-calculator.md",
    "category": "Science & engineering",
    "description": "Decode the colour bands on a 4-, 5- or 6-band resistor into its resistance, tolerance, minimum and maximum value and temperature coefficient.",
    "summary": "Read the bands from the end opposite the gold or silver tolerance band. The first two or three bands are digits, the next is the multiplier, then the tolerance.",
    "also_called": [
        "Resistor colour code calculator",
        "Resistor color code decoder"
    ],
    "applies_to": "Worldwide",
    "last_updated": "2026-10-29",
    "computation": "Results are computed in the visitor’s browser on the HTML page. This API describes the calculator; it does not compute results.",
    "inputs": [
        {
            "name": "bands",
            "label": "Number of bands",
            "type": "segmented",
            "default": "4",
            "options": {
                "4": "4 bands",
                "5": "5 bands",
                "6": "6 bands"
            }
        },
        {
            "name": "band1",
            "label": "Band 1 (first digit)",
            "type": "select",
            "default": "brown",
            "options": {
                "black": "Black (0)",
                "brown": "Brown (1)",
                "red": "Red (2)",
                "orange": "Orange (3)",
                "yellow": "Yellow (4)",
                "green": "Green (5)",
                "blue": "Blue (6)",
                "violet": "Violet (7)",
                "grey": "Grey (8)",
                "white": "White (9)"
            }
        },
        {
            "name": "band2",
            "label": "Band 2 (second digit)",
            "type": "select",
            "default": "green",
            "options": {
                "black": "Black (0)",
                "brown": "Brown (1)",
                "red": "Red (2)",
                "orange": "Orange (3)",
                "yellow": "Yellow (4)",
                "green": "Green (5)",
                "blue": "Blue (6)",
                "violet": "Violet (7)",
                "grey": "Grey (8)",
                "white": "White (9)"
            }
        },
        {
            "name": "band3",
            "label": "Band 3 (third digit, 5 and 6 bands only)",
            "type": "select",
            "default": "black",
            "options": {
                "black": "Black (0)",
                "brown": "Brown (1)",
                "red": "Red (2)",
                "orange": "Orange (3)",
                "yellow": "Yellow (4)",
                "green": "Green (5)",
                "blue": "Blue (6)",
                "violet": "Violet (7)",
                "grey": "Grey (8)",
                "white": "White (9)"
            }
        },
        {
            "name": "multiplier",
            "label": "Multiplier band",
            "type": "select",
            "default": "red",
            "options": {
                "black": "Black (×1)",
                "brown": "Brown (×10)",
                "red": "Red (×100)",
                "orange": "Orange (×1k)",
                "yellow": "Yellow (×10k)",
                "green": "Green (×100k)",
                "blue": "Blue (×1M)",
                "violet": "Violet (×10M)",
                "grey": "Grey (×100M)",
                "white": "White (×1G)",
                "gold": "Gold (×0.1)",
                "silver": "Silver (×0.01)"
            }
        },
        {
            "name": "tolerance",
            "label": "Tolerance band",
            "type": "select",
            "default": "gold",
            "options": {
                "brown": "Brown (±1%)",
                "red": "Red (±2%)",
                "orange": "Orange (±0.05%)",
                "yellow": "Yellow (±0.02%)",
                "green": "Green (±0.5%)",
                "blue": "Blue (±0.25%)",
                "violet": "Violet (±0.1%)",
                "grey": "Grey (±0.05%)",
                "gold": "Gold (±5%)",
                "silver": "Silver (±10%)",
                "none": "No band (±20%)"
            }
        },
        {
            "name": "tempco",
            "label": "Temperature coefficient band",
            "type": "select",
            "default": "brown",
            "options": {
                "brown": "Brown (100 ppm/K)",
                "red": "Red (50 ppm/K)",
                "orange": "Orange (15 ppm/K)",
                "yellow": "Yellow (25 ppm/K)"
            },
            "shown_when": {
                "bands": "6"
            }
        }
    ],
    "outputs": [
        {
            "key": "resistance",
            "label": "Resistance",
            "format": "text"
        },
        {
            "key": "ohms",
            "label": "In ohms",
            "format": "number"
        },
        {
            "key": "tolerance",
            "label": "Tolerance",
            "format": "number"
        },
        {
            "key": "min_ohms",
            "label": "Minimum value",
            "format": "number"
        },
        {
            "key": "max_ohms",
            "label": "Maximum value",
            "format": "number"
        },
        {
            "key": "tempco",
            "label": "Temperature coefficient",
            "format": "text"
        }
    ],
    "formula": {
        "text": "Resistance = (digits) × multiplier;  Range = Resistance × (1 ± tolerance ÷ 100). Digits: black 0, brown 1, red 2, orange 3, yellow 4, green 5, blue 6, violet 7, grey 8, white 9. Multiplier: 10^digit, gold × 0.1, silver × 0.01.",
        "variables": {
            "Tolerance": "brown ±1%, red ±2%, green ±0.5%, blue ±0.25%, violet ±0.1%, grey ±0.05%, gold ±5%, silver ±10%, no band ±20%"
        }
    },
    "worked_example": {
        "inputs": {
            "bands": "4",
            "band1": "brown",
            "band2": "green",
            "band3": "black",
            "multiplier": "red",
            "tolerance": "gold",
            "tempco": "brown"
        },
        "steps": [
            "Brown = 1 and green = 5 give the digits 15.",
            "Red multiplier = × 100, so 15 × 100 = 1,500 Ω = 1.5 kΩ.",
            "Gold = ±5%: 1,500 × 0.05 = 75 Ω, so 1,425 to 1,575 Ω."
        ],
        "result": "Brown-green-red-gold is a 1.5 kΩ resistor with ±5% tolerance, anywhere from 1,425 Ω to 1,575 Ω."
    },
    "interpretation": "Check a decoded value against the standard E-series (E12, E24…) values: if the result is not a standard value, you have probably read the bands from the wrong end. A multimeter settles any doubt.",
    "assumptions": [
        "IEC 60062 colour code as commonly used for through-hole resistors."
    ],
    "limitations": [
        "Grey and yellow tolerance markings vary between manufacturers and editions of IEC 60062 (grey is also used for ±0.01%); check the datasheet for precision parts.",
        "Surface-mount resistors use printed number codes, not colours."
    ],
    "rules": null,
    "faqs": [
        {
            "question": "Which end do I start from?",
            "answer": "Start from the end with the band closest to the edge. The tolerance band, often gold or silver, is usually separated by a wider gap and goes last."
        },
        {
            "question": "What does a single black band mean?",
            "answer": "A zero-ohm link: a jumper in a resistor body."
        }
    ],
    "sources": [
        {
            "title": "Colorado State University ECE: Standard resistor colour code",
            "url": "https://www.engr.colostate.edu/ECE103/FA13/general%20info/Standard%20Resistor%20color%20code.htm"
        },
        {
            "title": "TE Connectivity: Resistor colour codes",
            "url": "https://www.te.com/es/products/passive-components/resistors/intersection/resistor-color-codes.html"
        }
    ],
    "related": [
        {
            "name": "Ohm’s Law Calculator",
            "url": "https://calculators.geekmidst.com/calculators/ohms-law-calculator"
        },
        {
            "name": "Voltage Drop Calculator",
            "url": "https://calculators.geekmidst.com/calculators/voltage-drop-calculator"
        }
    ],
    "disclaimer": null,
    "publisher": "GM¹X CalcVerse"
}