Open-to-Buy (OTB)

Open-to-Buy is the dollar or unit budget a retail buyer has available to purchase new inventory in a given period, given the sales plan, current stock, and merchandise already on order. It is the financial control that answers "how much room is left to buy?" and is described by Blue Yonder (2026) as "the most critical output" of Merchandise Financial Planning (MFP) — the layer where planners convert a top-down financial sales target into a constrained purchasing budget. For a fashion/apparel retailer, it governs seasonal buying, markdown budgeting, and in-season reforecasting. In the UK and South Africa, the same concept is called WSSI (Weekly Sales, Stock and Intake) — OTB is the output of the WSSI process (Toolio, May 2026; Style Arcade, June 2026).

How it's calculated

Three formula variants coexist; the choice depends on whether the business plans OTB at retail, cost, or unit level (Shopify, March 2026; Toolio, May 2026):

Retail (revenue-based) formula — most common in fashion/apparel:

OTB (@ retail) = Planned Sales + Planned Markdowns + Planned EOM Stock − Planned BOM Stock − On Order

Blue Yonder (2026) and Shopify (March 2026) both report this variant, making markdowns an explicit line item. Converting to cost: Cost OTB = Retail OTB × (1 − IMU%) — e.g. retail OTB of $10,350 with 75% IMU → cost OTB = $2,587.50 (Shopify, March 2026).

Cost-based formula — used when finance manages cash flow in cost dollars:

OTB = Opening Stock + Intakes − Sales = Closing Stock

In this variant markdowns are embedded in the COGS/margin figure and no separate markdown row is required (Retail Dogma, updated May 2025; RELEX Solutions, June 2025).

Unit-based formula — used when physical space (planogram/store floor) is the binding constraint, not cash. Most planning teams run retail OTB as the primary view with cost OTB for finance alignment and unit OTB for floor-level decisions (Shopify, March 2026; Toolio, May 2026).

The most commonly omitted component in manual calculations is On Order — merchandise committed to suppliers but not yet received, which lives in email threads, supplier portals, and buyer memory (Toolio, May 2026; Linenow). A 5% deviation from planned OTB (either direction) is considered a good planning accuracy result (Retail Dogma, May 2025).

OTB in the MFP hierarchy

Blue Yonder (2026): "MFP acts as the 'Checkbook' of the retail organisation, preventing overbuying and underbuying." The hierarchy reported across sources:

S&OP (Sales & Operations Planning) sets the corporate revenue goal (top-down)
Merchandise Financial Planning (MFP) translates that into category-level financial guardrails — sales targets, margin goals, inventory targets
OTB translates MFP targets into actionable purchasing budgets for buyers — "telling buyers exactly how much they can commit at the category level and by when" (Toolio, May 2026)
Assortment Planning works within OTB limits to select styles, depths, and localisations
Replenishment / allocation executes at the SKU level within the assortment plan

RELEX Solutions (June 2025): "It is the essential bridge between top-down financial planning and bottom-up replenishment planning, ensuring both processes work harmoniously."

MFP metrics managed alongside OTB: Sales (revenue target), Receipts/Intake (dollar value of inventory arriving), Inventory/Stock (dollar value on shelves), Markdowns (discount budget), Gross Margin, Turnover (Blue Yonder, 2026).

The top-down / bottom-up tension

MFP resolves a structural conflict: the CFO/CEO sets a total revenue goal (top-down), while buyers and planners build category-level plans (bottom-up). The sum of all bottom-up plans must equal the top-down corporate goal. OTB is the reconciliation mechanism (Blue Yonder, 2026).

How fashion/apparel retailers use it

Pre-season vs in-season OTB

The fashion calendar has four main seasons: Spring/Summer (SS), Autumn/Winter (AW), Resort/Cruise, and Pre-Fall. The 6-month OTB planning cycle aligns to the SS/AW split — OTB is set twice a year and requires continuous in-season updating (Retail Dogma, May 2025).

At season start, total OTB is broken into an option plan — how many products to buy, at what average buy depth, and at what average RRP. For a vertical brand with $20M OTB: 200,000 units across 2,000 products at avg RRP $100 with avg 100 units per product (Style Arcade, June 2026).

60/40 pre-season/in-season split: Style Arcade (June 2026) reports a common approach of committing ~60% of OTB before the season and reserving ~40% for in-season trading — allowing the team to react to what is actually selling, place repeat orders on bestsellers, and spot opportunities. NRF/Amlani (December 2025) reports a similar but narrower reserve: "Leave 10%–15% of OTB to buy into in-season trends or replenish best sellers."

Vertical brand vs multi-brand OTB

Vertical brands (own design and production) have full control over the option plan — planners set exactly how many options and how much spend per category/product; design and production teams work within that framework. Multi-brand retailers split OTB across brands based on historical performance (prior-year sell-through and profitability): "If the range is strong, you might invest more; if it's weak, you pull back" (Style Arcade, June 2026).

Lead time and early commitment

Fashion wholesale buys committed in February for Fall season deliver in July — 6 months of capital locked at PO issuance. Key materials (fabric) can require commitment 18 months before product release (Retalon, June 2026; Retail Dogma, May 2025). Placing higher volumes early can unlock better supplier margins and allow sea rather than air freight, significantly reducing Landed Cost (Style Arcade, June 2026).

Merchant-driven vs budget-driven cultures

Retalon (June 2026) distinguishes two OTB cultures: merchant-driven organisations treat OTB as advisory — if buyers encounter the right product they may exceed the budget; budget-driven organisations require strict compliance. "Regardless of culture, the budget must be calculated."

OTB triggers (when to update mid-season)

Toolio (May 2026) identifies four triggers for an immediate OTB review:

Sales outpacing plan — receipts plan needs to increase to support higher sell-through; risk of stockouts mid-season
Sales lagging plan — ending inventory will be higher than planned; risk of excess stock destroying margin
Order cancellations — reopens OTB budget; buyers need to know room to fill
Lead time pressure — OTB without lead time awareness is incomplete; open capacity at week 12 of a 16-week lead time is unactionable

OTB release: clearing excess inventory to free buying budget for new product. Because future buys are determined by future sales minus current inventory, excess stock directly blocks new purchasing capacity (Retail Dogma, May 2025).

Tariff impact on cost OTB (2025–2026)

When tariffs shift, retail OTB can appear unchanged while cost OTB has narrowed because the same units now cost more at Landed Cost. Toolio (May 2026): "If you had $400,000 in cost OTB and your average landed cost just increased 15% due to new tariffs, the same units now cost more." Running only retail OTB without cost OTB during tariff volatility creates a false picture (as-of 2025–2026, volatile).

Key performance metrics

Inventory turns and OTB closing stock

OTB closing stock target is derived directly from the inventory turn target: if the business targets 3 turns/year → 4 months forward cover; if 2 turns/year → 6 months cover (Retail Dogma, May 2025).

Fashion specialty turns (as-of May 2025):

3–4 turns/year considered "good" for fashion retailers (Retail Dogma, May 2025)
4–6 turns/year is the ideal range for fashion specialty (Retail Dogma, May 2025)
Department stores: 12–14 weeks of supply (implied ~4 turns/year) (Retail Dogma, May 2025)
Mass market (Walmart/Target): 4–6 weeks of supply (implied ~8–12 turns/year) (Retail Dogma, May 2025)
Zara and H&M cited at ≈12× annually (as-of 2025, Onramp Funds)

Other benchmarks (as-of mid-2025 to 2026, volatile)

OTB planning accuracy: 5% deviation from planned OTB (either direction) is considered a good result (Retail Dogma, May 2025)
GMROI: Above $2.00 considered strong in most specialty retail; above $1.00 means the category covers its inventory cost (search result synthesis, Retail Dogma/StyleMatrix, mid-2025/2026)
Sell-through trigger for markdown review: if full-price sell-through falls below 40% at week 6 of a 12–14 week season, initiate a markdown review before the window to clear at margin closes (StyleMatrix, April 2026)
Omnichannel OTB: Deloitte (2026 Retail Distribution Industry Outlook, cited by Shopify) notes most retailers investing in integrated platforms to fix inventory visibility gaps; without real-time syncing, OTB decisions rest on outdated numbers (as-of 2026)

Tooling: spreadsheets vs systems

Major vendors offering MFP/OTB modules (as-of 2025–2026; all vendor self-description, conflict of interest applies):

RELEX Solutions — unified MFP/OTB integrating financial planning with replenishment; AI-powered; positions OTB as dynamic bridge between financial and supply planning
Blue Yonder — Merchandise Financial Planning product; unifies demand forecasting with inventory optimisation for promotion-aware planning; combines "predictive analytics, generative AI, and human insight" (Blue Yonder, 2026)
Anaplan — cloud-based scenario modelling; used where OTB must stay aligned across cross-functional teams; flexible rather than retail-native
Retalon — AI-powered retail planning with dedicated OTB module; integrates with Microsoft Dynamics 365; SOC 2 Type II; scenario planning + attribute-based planning + OTB vs. SOQ comparison
Toolio — cloud-based MFP for mid-market retailers; OTB, assortment, in-season tracking
Style Arcade — fashion-specific; WSSI/OTB tracking with visual assortment plan that updates OTB in real time as buying occurs
Oracle Retail MFP — RPAS-based enterprise system; widely deployed in large retail chains (Oracle Retail MFP documentation)
Manhattan Associates, Körber, Fluent Commerce — focus on WMS/OMS/order orchestration, not MFP/OTB (scope boundary confirmed by registry research, July 2026)

Gartner maintains a "Retail Merchandise Financial Planning" reviews market (Gartner Peer Insights, 2026). The Gartner Market Guide for Retail MFP (doc 6161423) is gated — flagged for manual download to _inbox/.

Spreadsheet tipping point: Canopy (vendor, undated) reports most brands hit difficulty between 200 and 500 SKUs — workable below 200, unreliable above 500. Style Arcade (June 2026): "While small, straightforward fashion businesses can operate using quarterly OTB in spreadsheets, brands and multi-brand retailers with complex assortments need WSSI capabilities to match the pace of modern retailing."

AI and agentic shift in OTB (2024–2026)

RELEX Solutions (June 2025) identifies fragmented systems as the primary OTB barrier: "Many companies manage their budgets in systems separate from their forecasting and replenishment planning systems. This requires manual exports, imports, and spreadsheet reconciliation, leading to delays." The McKinsey Global Merchant Survey (n=114, fielded December 2025) confirms: merchants still spend 40% of their time on low-value tasks including data consolidation and repetitive spreadsheet work across siloed systems (as-of December 2025, volatile).

McKinsey (January 2026) survey findings (as-of December 2025, volatile):

71% of merchants say AI merchandising tools have had "limited to no effect" on their business
61% say their organisation is "not at all or only slightly prepared to scale AI across merchandising"
Fewer than 10% use AI to assist with more than 50% of their merchandising decisions

AI-powered OTB improvements identified by RELEX (June 2025):

Continuous budget monitoring — financial and replenishment planning in one system; immediate visibility of current and projected orders vs. budgets
Proactive alerts — identifies potential budget overruns weeks or months in advance
Markdown modelling via Price Elasticity of Demand — modelling how markdowns change demand and therefore the OTB figure itself (Retalon, June 2026)

Anaplan (September 2025): the monthly OTB meeting is "no longer just inefficient — it's a competitive disadvantage." When decision-making can happen daily, waiting a month to approve or adjust creates planning lag where the window to act closes before the meeting happens.

RELEX (July 2026) published an "agentic AI guide for retail planning," signalling a direction toward autonomous AI agents that identify planning gaps and trigger actions — the next evolution beyond AI-powered alerts. This connects to the broader Agentic Commerce trend.

What practitioners report

[!unverified] Reddit MCP unavailable in both runs (June 2026 and July 2026). Practitioner perspectives on spreadsheet-vs-system adoption, in-season reforecasting discipline, and overbought/stuck-inventory pain remain an open gap. NRF/Amlani (December 2025) practitioner guidance is the closest proxy: "Avoid spending 100% of the OTB budget; leave 10–15% to buy into in-season trends or replenish bestsellers. Track purchase orders and keep a close eye on cash flow to prevent overspending."

Key terms

Term	Meaning
BOM / EOM stock	Beginning- / end-of-month inventory; EOM of month N = BOM of month N+1 (Shopify, March 2026)
On Order	Merchandise committed to suppliers but not yet received; most-omitted OTB component (Toolio, May 2026)
IMU	Initial Markup; converts retail purchases to cost (Shopify, March 2026)
WSSI	Weekly Sales, Stock and Intake — UK/South Africa name for the same concept (Style Arcade, June 2026; Toolio, May 2026)
Option plan	Breakdown of OTB into number of products × buy depth × average RRP (Style Arcade, June 2026)
OTR	Open-to-Receive — quantities and dates when merchandise shipments land; OTB sets the budget, OTR ensures products arrive when needed (StyleMatrix, April 2026)
MFP	Merchandise Financial Planning — the layer that sets OTB guardrails (Blue Yonder, 2026)
OTB release	Clearing excess inventory to free purchasing budget for new product (Retail Dogma, May 2025)

Frontier links

Merchandise Financial Planning (MFP) · Assortment Planning · Markdown Optimisation · GMROI · Sell-Through Rate · Weeks of Supply (WOS) · Initial Markup (IMU) · Open-to-Receive (OTR) · WSSI · Agentic Commerce