Simple buffer method
This method is easy to explain but can overstate or understate inventory for volatile demand. Service-level based safety stock needs demand variability data.
Example
If maximum daily use is 70, maximum lead time is 18 days, average daily use is 40 and average lead time is 12 days, safety stock is 70 x 18 - 40 x 12 = 780 units.
Common mistakes
Use realistic maximum values, not extreme one-off events unless you intentionally want a very conservative buffer.
Limitations
This calculator does not optimize service level, carrying cost, reorder quantity or supplier risk. It is a simple planning estimate.
Last reviewed: 2026-05-17