Reorder Point Calculator

Use this reorder point calculator to estimate when to reorder inventory, how much safety stock to keep, and whether your current stock position is enough to avoid stockouts. It combines daily demand, lead time, service level, inventory on hand, and ordering assumptions in one practical dashboard.

Reorder Point

Know the inventory level that should trigger a new purchase order.

Safety Stock

Estimate buffer stock based on demand and lead-time variability.

Inventory Dashboard

View charts, stock position, recommended order quantity, and alerts.

Export Reports

Print, save as PDF, or export results to Excel for follow-up.

Inventory and Demand Inputs

Optional product or SKU name for the report.
Purchase cost per unit.
Optional, used to estimate gross margin.
Average units sold or used per day.
Optional variability of daily demand. Use 0 if unknown.
Average days from ordering to receiving stock.
Optional lead-time variability in days.
Higher service levels increase safety stock.
Units physically available now.
Open purchase orders not yet received.
If empty, it will be estimated as daily demand × 365.
Administrative, logistics, or purchase-order cost.
Storage, insurance, capital cost, shrinkage, etc.
Leave blank to calculate statistically from variability inputs.

How to Use the Reorder Point Calculator

  1. Enter your average daily demand and supplier lead time in days.
  2. Add demand and lead-time variability if you have historical data.
  3. Select a target service level based on how much stockout risk your business can accept.
  4. Enter current stock on hand and units already on order to calculate your inventory position.
  5. Click Calculate Reorder Point to see whether you should reorder now and the suggested order quantity.

Main Formulas Used

Lead-Time Demand = Average Daily Demand × Supplier Lead Time.

Safety Stock = Z-score × √((Lead Time × Demand Variability²) + (Average Daily Demand² × Lead-Time Variability²)).

Reorder Point = Lead-Time Demand + Safety Stock.

Inventory Position = Current Stock on Hand + Units Already on Order.

EOQ Estimate = √((2 × Annual Demand × Ordering Cost) ÷ Annual Holding Cost per Unit).

Practical Example

If a product sells 40 units per day, supplier lead time is 12 days, and safety stock is estimated at 150 units, the reorder point is:

Reorder Point = (40 × 12) + 150 = 630 units.

This means a purchase order should normally be triggered when the inventory position reaches about 630 units.

Reorder Point FAQ

What is a reorder point?

A reorder point is the inventory level that signals when a new purchase order should be placed to avoid running out of stock before the next delivery arrives.

What is safety stock?

Safety stock is extra inventory kept as a buffer against demand spikes, supplier delays, inaccurate forecasts, or operational disruptions.

Why does lead time matter?

The longer it takes suppliers to deliver, the more inventory you need to cover demand while waiting for replenishment.

What service level should I choose?

A 95% service level is commonly used, but critical items or high-demand products may require a higher level such as 97.5% or 99%.

Is EOQ the same as reorder point?

No. Reorder point tells you when to order, while EOQ estimates how much to order based on ordering and holding costs.

Can I export the results?

Yes. You can print the report, save it as PDF, or export the main inputs and results to an Excel file.

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Disclaimer: This reorder point calculator is for educational and planning purposes only. Inventory decisions should also consider supplier reliability, minimum order quantities, shelf life, seasonality, cash flow, storage limits, and professional operational judgment.