Safety stock calculator

Safety stock is the buffer against running out while demand or delivery misbehaves. All four methods here run on one working-day axis: weekly figures divide or multiply by your days-in-week choice before any formula, so a weekly demand figure never meets a daily lead time unconverted. The combined formula weights both risks at once; the single-risk rows show what each contributes; and max minus average is the cover-the-worst-week rule, which usually holds more stock than the service-level rows. This is cycle service level arithmetic, not fill rate, and it assumes demand and lead time are roughly normal and independent. It is not a forecast and does not track seasonality, per-order quantities, or lot sizes.