{
    "name": "Weft Yarn Requirement Calculator",
    "url": "https://calculators.geekmidst.com/calculators/weft-yarn-requirement-calculator",
    "markdown": "https://calculators.geekmidst.com/calculators/weft-yarn-requirement-calculator.md",
    "category": "Textile & apparel",
    "description": "Calculate the weft yarn weight for a woven fabric from picks per inch, reed width, fabric length, wastage and the weft count in Ne, tex or denier.",
    "summary": "Every pick runs the full reed width, so weft length = picks per metre × fabric length × reed width. Multiply by the yarn’s weight per metre.",
    "also_called": [
        "Weft weight calculator",
        "Weft consumption calculator"
    ],
    "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": "ppi",
            "label": "Picks per inch (PPI)",
            "type": "number",
            "default": "80"
        },
        {
            "name": "reed_width_in",
            "label": "Reed width",
            "type": "number",
            "default": "63",
            "unit": "in"
        },
        {
            "name": "fabric_length",
            "label": "Fabric length",
            "type": "number",
            "default": "1000",
            "unit": "m"
        },
        {
            "name": "wastage",
            "label": "Wastage",
            "type": "number",
            "default": "3",
            "unit": "%",
            "optional": true
        },
        {
            "name": "count",
            "label": "Weft count",
            "type": "number",
            "default": "30"
        },
        {
            "name": "count_unit",
            "label": "Count system",
            "type": "select",
            "default": "ne",
            "options": {
                "ne": "Ne (English cotton count)",
                "tex": "Tex (g per 1000 m)",
                "denier": "Denier (g per 9000 m)",
                "nm": "Nm (metric count)",
                "dtex": "dtex (g per 10 000 m)"
            }
        }
    ],
    "outputs": [
        {
            "key": "weft_kg",
            "label": "Weft yarn needed",
            "format": "number"
        },
        {
            "key": "total_picks",
            "label": "Total picks",
            "format": "integer"
        },
        {
            "key": "weft_lb",
            "label": "Weft yarn needed",
            "format": "number"
        },
        {
            "key": "yarn_km",
            "label": "Total weft yarn length",
            "format": "number"
        },
        {
            "key": "g_per_metre",
            "label": "Weft weight per metre of fabric",
            "format": "number"
        }
    ],
    "formula": {
        "text": "Picks = PPI × 39.37 × Length (m);  Weft kg = Picks × Reed width (m) × (1 + Wastage%) × Tex ÷ 1,000,000",
        "variables": {
            "PPI": "picks per inch in the fabric",
            "Reed width": "width of the warp in the reed (1 in = 0.0254 m)",
            "Tex": "grams per 1000 m (Ne converts as 590.54 ÷ Ne)"
        }
    },
    "worked_example": {
        "inputs": {
            "ppi": "80",
            "reed_width_in": "63",
            "fabric_length": "1000",
            "wastage": "3",
            "count": "30",
            "count_unit": "ne"
        },
        "steps": [
            "Picks = 80 per inch ÷ 0.0254 m × 1,000 m = 3,149,606.",
            "Each pick is 63 in = 1.6002 m long, so weft length = 3,149,606 × 1.6002 × 1.03 = 5,191,200 m.",
            "Ne 30 = 590.54 ÷ 30 = 19.685 tex, so weight = 5,191,200 × 19.685 ÷ 1,000,000 = 102.19 kg."
        ],
        "result": "1,000 m of fabric at 80 PPI on a 63-inch reed in Ne 30 weft needs about 102.2 kg of weft including 3% wastage."
    },
    "interpretation": "Add warp and weft weights for the total yarn order; their sum divided by fabric area is a good cross-check against the fabric GSM.",
    "assumptions": [
        "Weft crimp is covered by using the reed width rather than the fabric width.",
        "Wastage is a percentage of the weft length."
    ],
    "limitations": [
        "Shuttleless looms with tucked-in or leno selvedges add a little extra weft per pick that is not modelled separately."
    ],
    "rules": null,
    "faqs": [
        {
            "question": "Why use reed width instead of fabric width?",
            "answer": "The weft is inserted across the reed and then the fabric narrows as the weft crimps, so reed width already includes weft crimp."
        },
        {
            "question": "Can I use denier for the weft?",
            "answer": "Yes. Choose denier as the count system; it is converted to tex as denier ÷ 9."
        }
    ],
    "sources": [],
    "related": [
        {
            "name": "Warp Yarn Requirement Calculator",
            "url": "https://calculators.geekmidst.com/calculators/warp-yarn-requirement-calculator"
        },
        {
            "name": "Yarn Count Ne to Tex Converter",
            "url": "https://calculators.geekmidst.com/calculators/yarn-count-ne-to-tex-calculator"
        },
        {
            "name": "Yarn Count Denier to Tex Converter",
            "url": "https://calculators.geekmidst.com/calculators/yarn-count-denier-to-tex-calculator"
        },
        {
            "name": "Fabric GSM Calculator",
            "url": "https://calculators.geekmidst.com/calculators/fabric-gsm-calculator"
        }
    ],
    "disclaimer": null,
    "publisher": "GM¹X CalcVerse"
}