Beginning-of-Period (BOP) Inventory Formula
How apparel planners define BOP — the opening inventory position that every planning calculation depends on.
What BOP Inventory measures
BOP is the inventory on hand at the start of a period. It carries forward from the prior period's EOP — making it the simplest "formula" on the site, but one of the most consequential inputs.
BOP (Period N) = EOP (Period N−1)BOP can be expressed at retail (for sales planning) or at cost (for inventory accounting). Most apparel planning happens at retail; GAAP requires the cost view.
Worked apparel example
May BOP = April EOP. If April closed with $1.1M at retail, May opens with $1.1M at retail.
BOP for this period is $1,100,000, carried from last period's EOP. Use at retail for sales planning, at cost for inventory accounting.
Why it matters
BOP is the starting position for SSR, OTB, WOS, and every other balance calculation. An incorrect or stale BOP distorts every downstream number. In spreadsheet-based planning, BOP is often frozen at plan submission and never updated as in-transit, cancellations, and adjustments flow in.
Related formulas
- EOP Inventory — prior period's close becomes this period's open
- Receipt Plan — the flow between BOP and EOP
- Stock-to-Sales Ratio — BOP divided by period sales
See BOP update live — not monthly — in RetailNorthstar.
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