Open to Buy Software: What It Does and When You Need It | Inventory Hero
·5 min readMerchandise Planning
Open to Buy Software: What It Does and When You Need It
Open to buy software automates your inventory buying budget from live sales and stock data. What it does, spreadsheet vs software, and what to look for.
Open to buy software calculates and maintains your open-to-buy budget automatically from live data: your planned sales, current on-hand inventory, and what you already have on order. Instead of rebuilding a spreadsheet each period, it keeps the number current as sales come in and orders arrive, so you always know how much you can still spend on new inventory without overbuying.
Do I need open to buy software or is a spreadsheet enough?
A spreadsheet is fine when you have few SKUs, simple seasonality, and can keep on-order updated by hand. Software earns its place as your catalog, seasonality, and number of open purchase orders grow, because the manual version goes stale exactly when accuracy matters. If you are regularly unsure how much you can safely buy, or your spreadsheet is always out of date, that is the signal to move to software.
Andrew Erickson is the founder of Inventory Hero. He has spent years working with Amazon FBA sellers on demand forecasting, restock planning, and the cash flow side of running a private-label brand. Inventory Hero exists because every spreadsheet-based inventory system he tried eventually broke — usually right before Q4.
Look for live sync of sales and inventory (so the number is current, not a snapshot), accurate on-order tracking (the input sellers most often get wrong), planning by category or product group, forecasting to set the sales plan, and a clear view of how much you can still buy per group. A tool that only recomputes a formula without live data is barely better than a spreadsheet.
Read article
Open to buy software automates your inventory buying budget from live sales and stock data, so you always know how much you can still spend without rebuilding a spreadsheet. The short version: it keeps the open to buy number current as sales move and orders arrive, a spreadsheet works at small scale but goes stale as complexity grows, and the features that matter are live data sync, on-order tracking, and per-category planning. Below is what it does, when you need it, and what to look for.
At its core, the software maintains the open-to-buy calculation for you. Rather than assembling planned sales, on-hand, and on-order into a spreadsheet each period, it:
Pulls live data on what is selling and what you hold.
Tracks what is on order so committed purchases reduce your available budget automatically.
Recomputes OTB continuously, so the number reflects reality today, not the day you last updated a sheet.
Plans by period and category, so you can see buying room by product group, not just in aggregate.
The result is a running, trustworthy answer to how much more you can buy, which is exactly the number a manual process struggles to keep accurate.
A spreadsheet is a legitimate starting point, and for a small, simple catalog it is enough:
Spreadsheet works when you have few SKUs, predictable demand, and can reliably update on-order by hand.
It breaks down as SKUs multiply, seasonality complicates the sales plan, and open purchase orders pile up, because keeping it current becomes a job in itself, and a stale OTB is worse than none (it gives false confidence).
The tell is simple: if your OTB spreadsheet is usually out of date, or you find yourself unsure how much you can safely buy, the manual approach has outgrown its usefulness.
Not all tools that mention open to buy actually keep the number live. The features that matter:
Live sales and inventory sync. The number is only useful if it reflects today's sales velocity and stock; a tool that imports a snapshot once is barely better than a spreadsheet.
Accurate on-order tracking. This is the input sellers most often get wrong, and forgetting committed POs makes OTB overstate your room to buy. The tool must track it cleanly.
Planning by category or product group. Aggregate OTB hides that your winners need budget and your slow movers do not; per-group planning fixes that, and pairs with product segmentation.
Forecasting. The sales plan drives OTB, so a tool that helps you forecast, not just record, is more useful.
A clear "how much can I buy" view. The output should be an obvious, actionable number, not a report you have to interpret.
A tool that only recomputes a formula without live data does not solve the real problem, which is keeping the number current.
One caution before you go shopping: most software marketed as "open to buy" is traditional retail ERP (Oracle Retail, Aptos, and similar) built for department-store chains, at department-store prices and complexity. It is not made for an Amazon seller. What you actually need is inventory-management software with live on-order tracking and per-category planning, which delivers the OTB discipline without the retail-enterprise baggage. Do not let the "open to buy" label steer you into a tool built for a different kind of business.
You do not have to buy software on day one. A sensible path:
Start with a simple OTB spreadsheet: columns for planned sales, target ending inventory, planned markdowns, beginning inventory, and on-order, with the open-to-buy formula computing the result per period.
Add a date-updated cell and a discipline of refreshing it, because a stale sheet is the failure mode.
Watch for the breaking point. When you find the sheet is always out of date, when tracking on-order by hand becomes a chore, or when you cannot see buying room by product group, you have outgrown it.
Then move to software that syncs the same inputs live, so the number maintains itself.
The spreadsheet teaches you what the number means and whether OTB discipline actually changes your buying; the software removes the manual upkeep once the discipline has proven its worth. Graduating in that order means you buy the tool because you understand the need, not on faith.
Open to buy software keeps your inventory buying budget live from real sales and stock data, so the "how much can I still spend" number is always current and actionable. A spreadsheet suffices for a small, simple catalog; software earns its place as SKUs, seasonality, and open POs grow. Prioritize live data sync, accurate on-order tracking, per-category planning, and forecasting. It is the tooling layer under open to buy and merchandise financial planning, and it complements your restock planning.