Accounting Stock Reorder Point (Per-Unit) Calculator
Calculate the reorder point for an individual stock item using average daily demand, supplier lead time, safety stock and current inventory.
Overview
Use this per-unit stock reorder point calculator to estimate the inventory level that should trigger replenishment for one item or SKU. Enter average daily demand, supplier lead time, a safety-stock buffer and current available stock to see the reorder point and any immediate shortfall.
How it works
The calculator estimates demand during the supplier lead time by multiplying average daily demand by lead time in days. It then adds safety stock to produce the reorder point. If current available stock is below that point, the difference is shown as units needed to reach the reorder level. Current stock cover is calculated by dividing available stock by average daily demand.
How to use this calculator
- 1Enter the item’s average daily demand in units.
- 2Add the usual supplier lead time in days.
- 3Set the safety stock buffer you want to keep.
- 4Enter the usable units currently in stock.
- 5Review the reorder point, stock cover and current shortfall.
Example Calculation
Average daily demand
12
Supplier lead time
10
Safety stock
30
Current available stock
100
Reorder point
150 units
With demand of 12 units per day and a 10-day lead time, expected lead-time demand is 120 units. Adding 30 units of safety stock gives a reorder point of 150 units. With 100 units available, the current shortfall is 50 units and stock covers about 8.3 days.
Frequently asked questions
What is a stock reorder point?
A reorder point is the inventory level at which you would normally place a replenishment order, allowing for expected demand while the supplier delivers and for a safety-stock buffer.
How is the reorder point calculated?
It is calculated as average daily demand multiplied by supplier lead time, plus safety stock.
Is the reorder point the same as the order quantity?
No. The reorder point tells you when to order. The quantity ordered may depend on minimum order quantities, target stock levels, forecast demand, storage limits and purchasing policies.
What should I include in current stock?
Include usable stock that is available to meet demand. Consider excluding damaged, reserved, quarantined or otherwise unavailable units according to your inventory policy.
Why is safety stock included?
Safety stock is a buffer that can help reduce stockout risk when demand is higher than average or deliveries take longer than expected.
How often should I review reorder points?
Review them whenever demand patterns, supplier lead times, seasonality, product availability or service-level targets change. Regular reviews are useful for fast-moving items.
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Assumptions and warnings
Assumptions
- Average daily demand is representative of expected future demand.
- Supplier lead time is reasonably consistent and is measured in calendar days.
- Safety stock is set separately to reflect the desired buffer for this item.
- Current stock represents usable, available units and does not account for stock already on order.
- Results are operational estimates for one stock item and do not set an economic order quantity.
Warnings
- This calculator provides an inventory planning estimate only; review demand changes, supplier reliability and open purchase orders before placing an order.