{
    "name": "Fabric Width Conversion Calculator",
    "url": "https://calculators.geekmidst.com/calculators/fabric-width-conversion-calculator",
    "markdown": "https://calculators.geekmidst.com/calculators/fabric-width-conversion-calculator.md",
    "category": "Textile & apparel",
    "description": "Convert the fabric length a pattern asks for at one width (say 45 in) into the length you need at another width (say 60 in), by equal area.",
    "summary": "If the pattern asks for a length at one width and your fabric is wider or narrower, the same area is length × width, so the new length is the old length × old width ÷ new width.",
    "also_called": [
        "Fabric yardage converter"
    ],
    "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": "length",
            "label": "Length the pattern asks for",
            "type": "number",
            "default": "2.5"
        },
        {
            "name": "length_unit",
            "label": "Length in",
            "type": "segmented",
            "default": "yd",
            "options": {
                "yd": "Yards",
                "m": "Metres"
            }
        },
        {
            "name": "from_width",
            "label": "Fabric width in the pattern",
            "type": "number",
            "default": "45"
        },
        {
            "name": "to_width",
            "label": "Width of your fabric",
            "type": "number",
            "default": "60"
        },
        {
            "name": "width_unit",
            "label": "Widths in",
            "type": "segmented",
            "default": "in",
            "options": {
                "in": "Inches",
                "cm": "Centimetres"
            }
        }
    ],
    "outputs": [
        {
            "key": "new_length",
            "label": "Length needed at your width",
            "format": "number"
        },
        {
            "key": "change_pct",
            "label": "Change in length",
            "format": "percent"
        },
        {
            "key": "area_m2",
            "label": "Fabric area",
            "format": "number"
        }
    ],
    "formula": {
        "text": "New length = Original length × Original width ÷ New width",
        "variables": {
            "Original length, width": "what the pattern envelope states",
            "New width": "the usable width of the fabric you are buying"
        }
    },
    "worked_example": {
        "inputs": {
            "length": "2.5",
            "length_unit": "yd",
            "from_width": "45",
            "to_width": "60",
            "width_unit": "in"
        },
        "steps": [
            "Area = 2.5 yd × 45 in; at 60 in wide the same area needs 2.5 × 45 ÷ 60 = 1.875 yd.",
            "1.875 ÷ 2.5 − 1 = −25%, so you need a quarter less fabric."
        ],
        "result": "2.5 yards of 45-inch fabric converts to 1.875 yards (about 1⅞ yd) of 60-inch fabric."
    },
    "interpretation": "Round up to the next cut your shop sells, and add extra for one-way designs, nap, pile or pattern matching, which an equal-area conversion cannot see.",
    "assumptions": [
        "Both widths are usable widths, excluding selvedges.",
        "Pattern pieces can be laid out as efficiently on either width."
    ],
    "limitations": [
        "Large pieces that do not fit across a narrow fabric need more length than the area rule suggests."
    ],
    "rules": null,
    "faqs": [
        {
            "question": "Is this the same as a fabric conversion chart?",
            "answer": "Yes. Printed charts are equal-area conversions rounded up to convenient fractions of a yard."
        },
        {
            "question": "Should I add extra?",
            "answer": "Add 10–15% for directional prints, velvet or plaid matching, and for pre-wash shrinkage."
        }
    ],
    "sources": [],
    "related": [
        {
            "name": "Fabric Shrinkage Percentage Calculator",
            "url": "https://calculators.geekmidst.com/calculators/fabric-shrinkage-percentage-calculator"
        },
        {
            "name": "Fabric Consumption per Garment Calculator",
            "url": "https://calculators.geekmidst.com/calculators/fabric-consumption-per-garment-calculator"
        },
        {
            "name": "Length Converter",
            "url": "https://calculators.geekmidst.com/calculators/length-converter"
        }
    ],
    "disclaimer": null,
    "publisher": "GM¹X CalcVerse"
}