Replenishment
calculator
ABOUT REPLENISHMENT CALCULATOR
This tool helps you find the best-for-profit inventory strategy — reorder point (ROP) and reorder quantity (ROQ) — based on your input data. Currently, it's optimized for desktop use and works best as an illustrative example. A tablet and mobile version is on our roadmap.
This calculator processes one item-location pair at a time. If you need bulk calculations across products and locations, just reach out — we’ll be happy to share more powerful options.
To begin, enter your data and click "Calc". Most fields are self-explanatory, but if you'd like more detail, you'll find explanations just below.
Product
parameters
ABOUT INPUT DATA
Purchase price – Price per unit, including all costs incurred before ownership transfer (customs, delivery, inspections, etc.).
Supplier payment terms – Days between delivery and payment due date. Default: 30 days. Valid input: 0–365.
Selling price – Average price paid by customers per unit during the selected period, based on invoiced transactions.
Customer payment terms – Time granted to customers to pay. Default: 0 days (typical for retail). Valid input: 0–365.
Replenishment cost – Cost per order, including order processing, receiving, and administrative handling. You can estimate it by dividing SG&A by the number of order lines over the period.
Average cost of capital – Average rate your company pays for capital or the return expected by shareholders. Used to calculate the cost of capital tied up in stock.
Delivery lead time – Time from placing the order to the goods being delivered and ready for sale. Valid range: 0–365 days.
Actual demand – Average daily sales, calculated from periods with no stock-outs. Input in units per day. Valid range: 0–100,000.
Demand quantity distribution – Describes how sales are split across transaction sizes. Example: If mineral water is usually sold by the bottle, it might be “1 – 100%”. If some customers buy boxes of 20, and those make up 66% of value, it could look like: “1 – 33%, 20 – 66%”.
Custom
parameters
ABOUT CUSTOM ROP/ROQ PARAMETERS
Compare with custom ROP/ROQ – Tick this box if you'd like to input your own reorder point and quantity and compare it with the optimized solution. Your results will appear in the "Custom" column of the results table.
KPIs that perform worse than optimal will be marked in red, while those that improve will be marked in orange.
ROP / ROQ fields under this section allow you to input your own parameters for side-by-side comparison.
Buttons
ABOUT BUTTONS FUNCTIONALITY
Calc – Runs the optimizer and calculates the best ROP, ROQ, and key KPIs for your setup.
Cost surface – Appears after calculation. On this screen, you can set step sizes and generate a 3D plot of total cost or profit as a function of ROP and ROQ. The minimum-cost or maximum-profit point is clearly marked.
Logistics curve – Also available after calculation. Displays the inventory curve over five reorder cycles based on your inputs.
Replenishment
plans
ABOUT THE RESULTS TABLE
Two columns are shown:
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Optimum – Based on the optimized ROP and ROQ.
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Custom – Based on user-inputted ROP and ROQ (if provided).
KPIs listed:
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Reorder point (ROP) – When to trigger a new order.
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Reorder quantity (ROQ) – How much to order at that point.
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Reorder cycle, days – Time between orders.
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Service level, % – How much demand is expected to be fulfilled.
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Inventory, days – Average inventory expressed in days of sales.
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Total daily costs – Combined daily cost of stock-outs, holding, and replenishment.
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Stock-out cost – Gross profit lost from unmet demand.
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Holding cost – Cost of frozen capital in inventory.
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Replenishment cost – Cost of placing and receiving the order.
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Profit per day – Maximum gross profit assuming all demand is met.
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Stock-out quantity – Unmet demand (in units).
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Ave. stock level, pcs – Average number of units in stock.
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Ave. inventory value – Inventory value based on purchase price.
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Maximum, pcs – Max stock quantity on the day of delivery.