Mastering Inventory Investment with an Open-To-Buy Budget

Last updated on:

March 16, 2025

Every retailer faces the same financial tightrope. Buy too much, and cash gets locked into stock that sits on shelves, eventually marked down at a loss. Buy too little, and customers walk away to a competitor who had the product in stock. Open to Buy, usually shortened to OTB, is the budgeting tool built to keep retailers balanced on that rope. It answers one of the most important questions in retail: how much more merchandise can I afford to buy right now without breaking my financial plan?

What is Open to Buy?
The unit of measure: thinking in money, not pieces
The Open to Buy formula
How Open to Buy works at different levels
From company down to sub-classification
Down to individual items for small retailers
Where OTB sits in the planning process
It starts with planning
It ties back to financial control
Why OTB matters for inventory investment

What is Open to Buy?

Open to Buy is a financial budget for retail merchandise. Its main job is to help a retailer manage and replenish what is often their single biggest asset: the money invested in inventory. For most stores, stock is where the largest chunk of working capital lives, so controlling it carefully is not optional. It is the difference between a healthy cash flow and a cash crunch.

OTB is best understood as a forward-looking tool. It is not a record of what already happened. Instead, it is a financial budgeting strategy used to calculate the money available for purchasing new inventory in a future period. It tells a buyer how much room is left in the budget after accounting for stock already on hand, sales that are expected, and orders already placed but not yet received.

Three features define what OTB does. First, it is future-oriented, focused on purchases yet to be made rather than past transactions. Second, it provides guidance on how much to buy, giving buyers a clear monetary ceiling for their commitments. Third, it offers benchmarks for evaluating progress, so a retailer can compare actual buying against the plan and spot when spending is drifting off course.

The unit of measure: thinking in money, not pieces

The unit of measure for Open to Buy is typically money. In the original textbook framing this is expressed in dollars, but the principle is currency-neutral. For a retailer in India, OTB is simply calculated in rupees. What matters is that the budget is tracked as a monetary value, not just as a count of items.

Retailers usually work with OTB in one of two monetary views. Retail OTB is expressed in the selling price of merchandise, which is useful for planning teams aligning purchases with sales targets. Cost OTB is expressed in what the retailer actually pays suppliers, which finance teams prefer when managing cash flow. According to a guide on OTB planning, most teams run the retail view as their main lens while keeping the cost view available for finance. Some retailers also track a unit view, counting actual pieces, especially when physical shelf space is the limiting factor.

The Open to Buy formula

The logic behind OTB becomes clear once you see the formula. A commonly used version is:

Open to Buy = Planned Sales + Planned Markdowns + Planned End-of-Month Inventory − Beginning-of-Month Inventory

Each part has a clear role. Planned sales is the projected sales value for the period, planned markdowns is the total value of discounts expected, and planned end-of-month inventory is the stock value you want to hold at the close of the period. You add these together to find the total inventory you need to support, then subtract the stock you already have at the start of the month. Whatever remains is the budget still “open” for buying.

Consider a simple example for a clothing department. Suppose planned sales for the month are ₹8,00,000, planned markdowns are ₹50,000, and the desired closing inventory is ₹6,00,000. The beginning inventory is ₹10,00,000. The OTB works out to ₹8,00,000 + ₹50,000 + ₹6,00,000 − ₹10,00,000 = ₹4,50,000. That ₹4,50,000 is how much the buyer can still commit to new merchandise this month.

In practice, retailers often refine this further by also subtracting merchandise already on order but not yet delivered. One version of the calculation subtracts both inventory already delivered in the period and planned receipts from open orders, which prevents a buyer from accidentally committing money that is already promised to a supplier.

How Open to Buy works at different levels

One of the most useful qualities of OTB is its flexibility. It can operate at any level of the business a retailer needs. The same logic scales up or down across the merchandise hierarchy.

From company down to sub-classification

A large retailer can run OTB at the company level to set an overall ceiling on inventory spending. That figure can then be broken down by department, such as menswear or home furnishing. Within a department, OTB can be split by classification, for example shirts or trousers, and then further into sub-classification, such as formal shirts versus casual shirts. This mirrors the way retail organisations structure merchandise, moving from broad groups down to narrower categories.

A merchandise planning approach like this lets a buying plan be created for the whole business and then divided into departments, categories, or even classes if needed. The more granular the level, the more precise the buying decisions become, because each slice of the budget is matched to the demand for that specific group of products.

Down to individual items for small retailers

For a small retailer, OTB can be taken right down to the individual item. A boutique owner or a single-store operator does not need an elaborate hierarchy. They can track open-to-buy for specific products, because their assortment is small enough to manage line by line. Small shops can run their OTB on quarterly spreadsheets, while large, complex assortments usually need more advanced software to keep up.

This adaptability is what makes OTB so versatile. A national chain and a neighbourhood store can both use the same underlying concept, simply applied at the level of detail that suits their size and complexity.

Where OTB sits in the planning process

Open to Buy does not exist in isolation. It begins with the planning process and ties back to financial control, sitting right in the middle of these two activities.

It starts with planning

OTB grows directly out of merchandise financial planning. Before a season begins, retailers forecast sales, decide how much inventory investment they need, and set gross margin goals. Open-to-buy management is described as a critical component of this planning that allocates budgets for future merchandise purchases by analysing sales projections, inventory positions, and financial goals. In other words, the high-level plan sets the targets, and OTB converts those targets into a usable buying budget.

This is the bridge function of OTB. A merchandise financial plan on its own is abstract; it talks about sales and margin goals at a department level. OTB translates these into a concrete number a buyer can act on. It converts receipt targets into buyable budgets at the department, class, or category level, giving buyers clear financial guardrails as they build their assortment plans.

It ties back to financial control

Once buying is underway, OTB becomes a control mechanism. As merchandise is purchased and received, the open-to-buy figure shrinks, showing exactly how much budget remains. This keeps actual purchases in line with the plan throughout the season. A buyer who watches their OTB closely knows immediately when they are running out of room and must stop committing money.

This control role is why OTB is treated as an inventory management discipline, not just a one-time calculation. A buyer must remain fiscally responsible, ensuring purchases stay in line with seasonal plans before the season and with the open-to-buy during the season. The figure is recalculated as conditions change, so it stays accurate as sales come in faster or slower than expected.

Why OTB matters for inventory investment

The bigger picture is cash flow. Inventory is expensive to hold, and money tied up in unsold stock cannot be used for anything else. A purchase budget exists to ensure a company has the right materials and inventory to fulfil budgeted sales, and OTB is the retail-specific version of that discipline.

For a price-sensitive market, where margins are often thin and competition is fierce, this control is especially valuable. Merchandise control is a critical aspect of retail management, and the Open to Buy system is an effective tool for managing inventory and purchasing. By buying proportionately to expected sales, a retailer avoids both the trap of dead stock and the lost revenue of empty shelves. The result is healthier cash flow, fewer forced markdowns, and the financial flexibility to react quickly when a new trend appears.

Open to Buy, then, is far more than a formula. It is a planning tool at the start of a season, a control tool during it, and a constant guardian of the most valuable asset a retailer owns. Used well, it turns inventory from a risk into a managed investment.

What do you think? If you were running a small store with limited cash, would you track Open to Buy at the item level for precision, or keep it simple at the category level to save time? And how might fast-changing customer demand force a retailer to revise their OTB mid-season rather than sticking to the original plan?

References

PDF 📄

Mastering Inventory Investment with an Open-To-Buy Budget

Table of Contents

What is Open to Buy? 🔗

The unit of measure: thinking in money, not pieces 🔗

The Open to Buy formula 🔗

How Open to Buy works at different levels 🔗

From company down to sub-classification 🔗

Down to individual items for small retailers 🔗

Where OTB sits in the planning process 🔗

It starts with planning 🔗

It ties back to financial control 🔗

Why OTB matters for inventory investment 🔗