Business Central Reorder Point and Safety Stock Calculator
Business Central's reordering policies need numbers on every item or stockkeeping unit: Reorder Point, Safety Stock Quantity, Reorder Quantity and Maximum Inventory. This calculator derives them from demand history, lead time and a service level instead of guesses.
Your numbers
Your results
Assumes normally distributed daily demand and constant lead time. Business Central also applies Lead Time Calculation, Safety Lead Time and Lot Accumulation Period in its planning run.
Safety stock and reorder point vs lead time
Sweeps Replenishment lead time from 1 to 60, holding your other inputs fixed.
Bulk-calculate planning parameters
Optional: we can compute reorder parameters for your whole item list from BC data.
Optional. The tool and every export work without this. No spam.
How to use it
Pull average daily demand and its standard deviation from item ledger entries, using at least six months of data. Enter your supplier lead time in days, choose the service level, and add ordering and holding cost to get an economic order quantity. Copy the outputs into the item card: reorder point and safety stock, reorder quantity or maximum inventory depending on your policy.
The formulas
Safety stock is z times the daily demand standard deviation times the square root of lead time. Reorder point is demand during lead time plus safety stock. Economic order quantity is the square root of two times annual demand times order cost, divided by annual holding cost per unit. Maximum inventory is the reorder point plus the order quantity, a common setting for the Maximum Qty. policy.
- Fixed Reorder Qty.: uses Reorder Point and Reorder Quantity
- Maximum Qty.: uses Reorder Point and Maximum Inventory
- Order: plans to demand and ignores reorder point
- Lot-for-Lot: plans to demand with optional safety stock
Reading the chart
Safety stock grows with the square root of lead time, while demand during lead time grows linearly, so long lead times dominate the reorder point. A cheaper way to cut inventory is often a shorter lead time, not a lower service level. Rerun with a different supplier lead time to see the saving.
Common mistakes
Using average monthly demand without its variability, forgetting that safety stock covers lead time variation as well, and leaving Reorder Point on items set to Lot-for-Lot. Also remember Include Inventory and the planning worksheet: if purchase orders already cover the demand, the planning run will not propose a new one.
Frequently Asked Questions
Which BC fields do I fill in?
On the item card or stockkeeping unit under Planning: Reordering Policy, Reorder Point, Reorder Quantity or Maximum Inventory, and Safety Stock Quantity. Safety Lead Time is a separate time buffer.
Why use a normal distribution?
It is the standard simplification for fast-moving items. For intermittent demand or very low volume, use a lot-for-lot policy with a small safety stock, or use a different distribution.
How many days of history should I use?
At least 6 to 12 months of daily or weekly demand, removing one-off events such as a bulk order. Too little data underestimates variability.
Does the planning run honour these values?
Yes. The planning worksheet and requisition worksheet use them to propose orders. Check calendars, lead time calculations and any existing supply that changes the result.
If you want these parameters calculated for thousands of items from live BC history and written back after approval, that is a job a read-only data extract and a small script can do for you.
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