{
    "name": "Production Material Requirement Calculator",
    "url": "https://calculators.geekmidst.com/calculators/production-material-requirement-calculator",
    "markdown": "https://calculators.geekmidst.com/calculators/production-material-requirement-calculator.md",
    "category": "Manufacturing & packaging",
    "description": "Work out how many units to start and how much material to order to finish a target number of good units after an expected scrap rate.",
    "summary": "If a share of what you start is scrapped, you must start more than you need. Divide the good units required by (1 − scrap rate), then multiply by material per unit.",
    "also_called": [
        "Scrap allowance calculator",
        "Raw material requirement 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": "good_units",
            "label": "Good units required",
            "type": "number",
            "default": "10000"
        },
        {
            "name": "scrap",
            "label": "Expected scrap (share of units started)",
            "type": "number",
            "default": "4",
            "unit": "%"
        },
        {
            "name": "per_unit",
            "label": "Material per unit",
            "type": "number",
            "default": "0.25"
        },
        {
            "name": "on_hand",
            "label": "Material already in stock",
            "type": "number",
            "default": "500",
            "optional": true
        }
    ],
    "outputs": [
        {
            "key": "starts",
            "label": "Units to start",
            "format": "integer"
        },
        {
            "key": "gross_material",
            "label": "Gross material required",
            "format": "number"
        },
        {
            "key": "net_material",
            "label": "Material to order (after stock)",
            "format": "number"
        },
        {
            "key": "scrap_units",
            "label": "Expected scrapped units",
            "format": "integer"
        }
    ],
    "formula": {
        "text": "Starts = ⌈Good ÷ (1 − Scrap%)⌉;  Gross material = Starts × Material per unit;  Net = Gross − Stock",
        "variables": {
            "Scrap%": "share of units started that end up scrapped"
        }
    },
    "worked_example": {
        "inputs": {
            "good_units": "10000",
            "scrap": "4",
            "per_unit": "0.25",
            "on_hand": "500"
        },
        "steps": [
            "Starts = 10,000 ÷ 0.96 = 10,416.7, rounded up to 10,417.",
            "Material = 10,417 × 0.25 = 2604.25.",
            "To order = 2604.25 − 500 = 2104.25."
        ],
        "result": "To finish 10,000 good units at 4% scrap, start 10,417 and order 2104.25 units of material."
    },
    "interpretation": "Dividing by (1 − scrap) is not the same as adding the scrap percentage: adding 4% would give 10,400 starts and leave you short.",
    "assumptions": [
        "Scrap is a share of units started, not of good units.",
        "Every unit uses the same material, whether it ends up good or scrap."
    ],
    "limitations": [
        "For multi-step processes, apply each step’s scrap rate in turn, starting from the last step."
    ],
    "rules": null,
    "faqs": [
        {
            "question": "Why not just add 4%?",
            "answer": "Because the 4% is lost from the larger starting quantity. 10,400 × 0.96 = 9984, short of 10,000."
        },
        {
            "question": "What if my scrap rate is quoted on good output?",
            "answer": "Then multiply good units by (1 + rate) instead."
        }
    ],
    "sources": [],
    "related": [
        {
            "name": "Production Yield Calculator",
            "url": "https://calculators.geekmidst.com/calculators/production-yield-calculator"
        },
        {
            "name": "Material Inventory Days Calculator",
            "url": "https://calculators.geekmidst.com/calculators/material-inventory-days-calculator"
        },
        {
            "name": "Board Reel Usage Calculator",
            "url": "https://calculators.geekmidst.com/calculators/board-reel-usage-calculator"
        },
        {
            "name": "Batch Manufacturing Cost Calculator",
            "url": "https://calculators.geekmidst.com/calculators/batch-manufacturing-cost-calculator"
        }
    ],
    "disclaimer": null,
    "publisher": "GM¹X CalcVerse"
}