Product Inventory Manager Calculator

Lead Time Demand multiplies daily usage — weekly usage divided by seven (lines 20-26) — by Supplier Lead Time in days (line 26). Safety Stock equals one full week of usage (line 29). Reorder Point adds those two figures (line 32), so a seven-day lead time with default usage yields a threshold of lead-time demand plus one week of buffer stock before you must place another order.

Yes. Both inputs multiply together to form weekly usage (line 17), which feeds lead-time demand and safety stock (lines 26-29). At equal fractional change, each input contributes identically to the reorder threshold — the formula is a symmetric product (reorder point = usage per service x services per week x a lead-time factor), so doubling usage per service alone produces exactly the same reorder point as doubling services per week alone. Neither one is the stronger lever.

Needs Reorder Now is one when Current Stock in units is less than or equal to the computed Reorder Point, and zero otherwise (line 41). Current stock does not change the reorder point itself — it only determines whether you have already crossed the threshold. Days of Stock Left divides current stock by daily usage separately (line 38) to show runway even when you are not yet at the reorder line.

Usable Before Expiry multiplies monthly usage by Shelf Life in months (line 50). Potential Waste Units is current stock minus that usable amount, floored at zero (line 51). Potential Waste Dollars multiplies those excess units by Cost Per Unit (line 52). Overstocking slow movers or products with short shelf life therefore shows up as dollar exposure even when reorder timing looks healthy.