Inventory management is the day-to-day work of receiving, storing, tracking, counting and valuing stock, so that a business knows at any moment what it holds, where each unit physically sits and what that stock is worth. Inventory planning decides what that stock should be: how much to hold, at which location, and when to order, move or mark it down.
Many companies run inventory management in an ERP and a warehouse management system (WMS), and inventory planning in spreadsheets, a planning module or a dedicated planning platform. The terms are often used interchangeably, and some authors fold forecasting into “inventory management”. This guide splits them the way the systems do, since that’s where one job hands off to the other.
What Is Inventory Management (Stock Management)?
Inventory management (also called stock management; the two terms mean the same thing) covers every physical and financial event that changes the stock record. Goods arrive and get checked against the purchase order, with shortages, overages and damage logged at the dock. They’re put away in a bin, a back room or a shelf. They’re picked, packed, shipped, transferred, returned, written off or counted. Each event updates quantity, location and value.
An inventory management system is the software that records those events. In practice the ERP and the WMS split that job:
- The ERP holds the financial and commercial record: item master, purchase orders, sales orders, stock by site, and inventory valuation for the books.
- The WMS holds the physical record inside a warehouse or distribution center (DC): bins and locations, putaway, picking, cycle counts and the labor to do it.
Smaller businesses often run everything in the ERP or in a commerce platform’s inventory module. Larger ones add a WMS once warehouse volume or complexity outgrows what the ERP’s inventory functions handle well.
Good inventory management answers questions about the present and the past. How many units of this SKU are in DC 3? Did the delivery from yesterday match the order? What is our stock worth at month end? It doesn’t answer how many units DC 3 should hold next Tuesday.
What Is Inventory Planning?
Inventory planning is the set of decisions that sets future stock: how much to buy, where to put it and when. The core decisions are:
- Forecasting demand by item, location and period, including promotions, seasonality and events.
- Safety stock and targets sized to forecast error, lead-time variability and the service level you want.
- Replenishment, the recurring decision on when to reorder and how much (the inventory replenishment guide covers the methods and formulas).
- Allocation of new or limited stock across stores, DCs and channels.
- Rebalancing and transfers when stock sits in the wrong place.
- Markdowns and clearance for seasonal, slow-moving or short-life stock.
Every one of those decisions reads the stock record that inventory management keeps, and every one of them ends as a transaction the ERP or WMS executes: a purchase order, a transfer, a price change.
What Is the Difference Between Inventory Management and Inventory Planning?
Inventory management records and controls the stock you have; inventory planning decides the stock you should have. Management is measured by how accurate and efficient the record and the warehouse are. Planning is measured by whether the right stock was in the right place at the lowest cost.
| Inventory management | Inventory planning | |
|---|---|---|
| Question answered | What do we have, where is it, what is it worth? | What should we have, where, and when do we order or move it? |
| Time horizon | Now and the past: today’s transactions, month-end valuation | Days to seasons ahead: next order, next promotion, next season |
| Typical system | ERP (record, purchase orders, valuation) and WMS (bins, picking, counts) | Planning platform or ERP planning module; often spreadsheets |
| Typical owner | Warehouse and store operations, inventory control, finance for valuation | Demand planners, supply and inventory planners, replenishment and merchandise planners |
| Key metrics | Record accuracy, receiving and putaway time, pick accuracy, shrink | Forecast error and bias, availability or fill rate, inventory days or turns, lost sales, excess and obsolete stock |
Planning depends on the record. A planning system fed a wrong stock record will order wrong, however good its forecast. A well-run warehouse can still hold the wrong stock if nobody planned it well.
Where ERP and WMS Stop and Planning Starts
ERPs and WMSs are systems of record and execution. They’re built to post transactions correctly, keep an audit trail and run operations at volume. They do contain planning features: reorder points, min-max levels, MRP runs. Those features usually rely on parameters a person sets and revisits by hand.
The ERP can raise a purchase order when the inventory position (on hand plus on order) falls below a reorder point. The reorder point itself stays where someone set it, even when a promotion starts next week, the supplier has been two days late for a month and the online channel is pulling from the same DC. A min-max level set for last year’s demand keeps ordering to last year’s demand until someone notices.
What a planning platform adds
A planning platform recalculates the parameters themselves, item by item and location by location, from current data. On Solvoyo’s inventory planning side, safety stock is sized from actual forecast error, lead-time variability and supply uncertainty, and targets recalibrate as conditions change. Multi-echelon optimization sets targets across suppliers, DCs and stores at once. The forecasts come from demand planning, which takes in promotions, events and weather.
A planner who has to correct most suggested orders will go back to the spreadsheet, so recommendation quality decides whether the layer gets used at all. The user acceptance rate, the share of recommendations planners accept without edits, is the plain test of whether the planning layer is working.
How a planning platform connects to ERP and WMS
The planning layer sits beside the ERP and WMS and replaces neither. Solvoyo’s integration options cover four routes:
- RFC (Remote Function Call) for SAP, so master data, transactions and plans flow between SAP and the planning platform without custom middleware.
- Web service APIs using SOAP (XML) or REST (JSON), for real-time or event-driven exchange.
- Direct database-to-database transfer via ODBC and SSIS for high-volume loads.
- Integration middleware such as Dell Boomi and MuleSoft, for companies that already run an iPaaS layer.
Scheduled or event-driven jobs pull data over an encrypted connection, run the optimization and write results back. With SAP, the ERP stays the system of record and no full data migration is needed. Approved recommendations then become executable transactions in the ERP and WMS, and live ERP and WMS data flows back so the next recommendation reflects current stock.
Inventory Management for Ecommerce and Omnichannel
Ecommerce inventory management is the same receiving, tracking and valuing work applied to online orders, with two complications: online demand moves on different signals, and online orders often draw on the same stock as stores.
On the demand side, online sales respond to site visits, click rates, conversion and competitor prices, which store history doesn’t show. Solvoyo’s omnichannel inventory and replenishment solution forecasts online demand from those online-specific drivers, and its e-commerce planning adds web analytics and promotional calendars to sales history.
On the supply side, shared stock creates a choice. If every store unit is visible to the website, online orders can strip a store before walk-in customers arrive. A virtual safety stock sets aside part of the store’s inventory for walk-in customers, and the platform then finds the most cost-effective way to fill the online order from what remains. Returns matter more online too; expected return rates by category and season feed back into the recommendations.
The management side (pick, pack, ship, receive returns) still runs in the WMS or the commerce platform. The planning side decides which location should serve which demand.
Signs the Problem Sits in Planning
These signs point to the planning side:
- Stockouts and overstock on the same items at different sites. The total is fine; the placement is wrong.
- Min-max or reorder levels nobody has touched in a year. Demand moved and the parameters didn’t.
- Planners overriding most system orders. The recommendations don’t reflect promotions, events or local demand.
- Excess builds after every season. Buys were set on last year’s numbers, and markdowns start too late. Pricing and markdown optimization addresses the timing and depth of that last step.
If the stock record itself is wrong (cycle counts disagree with the system, or phantom inventory blocks reorders), fix that first, because every planning method orders against the record.
What It Looks Like in Practice
A101’s replenishment was manual and its DC purchasing depended on people. It moved demand-driven replenishment and DC purchasing onto one planning platform, and across that scope reduced stock-outs by 50% and inventory by 18%.
Guides in This Series
This page is the hub for a set of guides on inventory decisions:
- Inventory replenishment: methods, formulas and how to prevent stockouts: reorder point, min-max, periodic review and demand-driven replenishment.
- Excess and obsolete inventory: why it builds and how planning prevents it.
- Inventory turnover: how to calculate it and what a good number depends on.
- Food and beverage supply chain best practices: shelf life, promotions and seasonal peaks.
Frequently Asked Questions
Yes. Stock management and inventory management describe the same work: receiving, storing, tracking, counting and valuing goods. Which word a company uses is mostly habit and region. Both differ from inventory planning, which decides how much stock to hold, at which location, and when to order, move or mark it down.
Partly. Most ERPs include reorder points, min-max levels and MRP runs, which can trigger purchase orders automatically. Those rules usually run on parameters that people set and review periodically, so they drift as demand, lead times and channels change. A planning platform recalculates the parameters from current data and sends the resulting orders back to the ERP to execute.
The ERP keeps the business record of inventory: item master, purchase and sales orders, stock by site and inventory value for accounting. The WMS runs the physical side inside a warehouse: bin locations, putaway, picking, packing and cycle counts. Many companies run inventory only in the ERP until warehouse volume or complexity justifies adding a WMS.
No. A planning platform connects to the ERP and WMS instead of replacing them. Solvoyo connects through RFC for SAP, web service APIs, direct database transfer or existing middleware. It reads stock, orders and master data, runs the planning, and writes approved orders back, so SAP or another ERP keeps the record.
