{
  "slug": "ecommerce-reorder-point",
  "title": "Inventory Reorder Point Calculator",
  "heading": "Reorder Point Calculator",
  "category": "financial",
  "url": "https://www.revenuelab.fyi/toolbox/ecommerce-reorder-point",
  "summary": "The inventory level that triggers a new purchase order before you stock out.",
  "description": "Reorder point tells you exactly how many units you should have on hand when you place a new purchase order, so the replenishment arrives before you run out, accounting for both average demand during the lead time and a safety buffer for demand spikes or shipping delays. Getting this wrong in either direction is expensive: too low and you stock out and lose sales; too high and you tie up cash in excess inventory sitting in a warehouse. This calculator takes your average daily sales velocity, supplier lead time in days, and a safety stock buffer, and computes the exact unit count at which you should trigger reordering. Enter average daily units sold, lead time in days from order to received inventory, and safety stock units (calculated separately or estimated). The output shows your reorder point and, given a specified order quantity, roughly how many days of coverage that order provides once it lands, so you can time purchase orders against your actual sales velocity rather than reordering on a fixed calendar schedule.",
  "formula": "Reorder point = (average daily sales × lead time days) + safety stock.",
  "dateModified": "2026-09-30",
  "run_url": "https://www.revenuelab.fyi/api/public/calc?tool=ecommerce-reorder-point",
  "inputs": [
    {
      "id": "avgDailySales",
      "label": "Average daily sales",
      "kind": "number",
      "hint": null,
      "default": 22,
      "unit": "units",
      "min": 0,
      "max": null
    },
    {
      "id": "leadTime",
      "label": "Supplier lead time",
      "kind": "number",
      "hint": null,
      "default": 35,
      "unit": "days",
      "min": 0,
      "max": null
    },
    {
      "id": "safetyStock",
      "label": "Safety stock",
      "kind": "number",
      "hint": null,
      "default": 150,
      "unit": "units",
      "min": 0,
      "max": null
    },
    {
      "id": "orderQty",
      "label": "Typical reorder quantity",
      "kind": "number",
      "hint": null,
      "default": 1500,
      "unit": "units",
      "min": 0,
      "max": null
    }
  ],
  "outputs": [
    {
      "id": "reorderPoint",
      "label": "Reorder point",
      "format": "number",
      "hint": null,
      "primary": true
    },
    {
      "id": "leadTimeDemand",
      "label": "Expected demand during lead time",
      "format": "number",
      "hint": null,
      "primary": false
    },
    {
      "id": "daysCoverage",
      "label": "Days of coverage per reorder",
      "format": "number",
      "hint": null,
      "primary": false
    }
  ],
  "worked_example": {
    "inputs": [
      "Average daily sales: 22 units",
      "Supplier lead time: 35 days",
      "Safety stock: 150 units",
      "Typical reorder quantity: 1500 units"
    ],
    "outputs": [
      "Reorder point: 920",
      "Expected demand during lead time: 770",
      "Days of coverage per reorder: 68"
    ]
  },
  "how_to": {
    "title": "How to use this",
    "steps": [
      "Enter average daily sales (units).",
      "Enter supplier lead time (days).",
      "Enter safety stock (units).",
      "Enter typical reorder quantity (units).",
      "Read your reorder point on the right — it updates as you type.",
      "Hit Share to keep the scenario or send it to someone."
    ]
  },
  "scenarios": [
    {
      "name": "Conservative",
      "description": "Lower-end numbers — what if things land soft?",
      "values": {
        "avgDailySales": 13,
        "leadTime": 21,
        "safetyStock": 90,
        "orderQty": 900
      }
    },
    {
      "name": "Typical",
      "description": "Defaults — the most common real-world setup.",
      "values": {
        "avgDailySales": 22,
        "leadTime": 35,
        "safetyStock": 150,
        "orderQty": 1500
      }
    },
    {
      "name": "Ambitious",
      "description": "Higher-end numbers — what if things really pop?",
      "values": {
        "avgDailySales": 35,
        "leadTime": 56,
        "safetyStock": 240,
        "orderQty": 2400
      }
    }
  ],
  "limitations": [
    "Results are estimates before tax, fees, and inflation unless an input explicitly covers them.",
    "Rates are treated as fixed for the whole period — variable-rate products will drift from this projection.",
    "This is educational maths, not financial advice. Check anything contractual with the lender or your accountant."
  ],
  "faq": [
    {
      "q": "How do I calculate safety stock if I don't already have a number?",
      "a": "Use a dedicated safety stock calculation based on demand variability and lead time variability rather than guessing. A common simple approach is to multiply your average daily sales standard deviation by a service-level factor (often 1.65 for ~95% service level) and by the square root of lead time in days."
    },
    {
      "q": "Should I use average lead time or worst-case lead time?",
      "a": "Average lead time for the reorder point calculation itself, with the variability captured separately in your safety stock buffer. Using worst-case lead time in both places double-counts the risk and leads to excess inventory."
    },
    {
      "q": "How often should I recalculate reorder points?",
      "a": "Monthly for stable SKUs, and immediately after any change in supplier lead time, a seasonal demand shift, or a meaningful change in sales velocity from a promotion or new sales channel. Stale reorder points are one of the most common causes of preventable stockouts."
    },
    {
      "q": "What if my sales velocity varies a lot by season?",
      "a": "Calculate reorder points separately for peak and off-peak periods using the seasonal average daily sales for the upcoming lead time window, not a trailing 12-month average that blends high and low seasons together."
    }
  ],
  "related": [
    "https://www.revenuelab.fyi/toolbox/safety-stock-calculator",
    "https://www.revenuelab.fyi/toolbox/eoq-calculator",
    "https://www.revenuelab.fyi/toolbox/sell-through-rate"
  ],
  "license": "CC-BY-4.0",
  "citation": "RevenueLab — Inventory Reorder Point Calculator (https://www.revenuelab.fyi/toolbox/ecommerce-reorder-point)"
}