Inventory management for ecommerce: forecast demand and keep stock accurate
Inventory is usually the biggest investment an online store makes. Hold too little and you sell out of best-sellers, lose sales and damage marketplace rankings. Hold too much and cash sits on shelves, storage costs rise and slow stock ends up discounted. Good inventory management keeps the right products in stock at the right levels, across every channel you sell on.
This guide covers stock tracking, forecasting, reorder points, multichannel sync and keeping counts accurate.
Know what you have and where it is
Every product needs a unique SKU, and every unit needs a known location. Record stock as it arrives, as it is sold and as it is returned, so your system always reflects reality. Barcode scanning at goods-in, picking and returns removes most manual errors.
Forecasting demand
Forecasting starts with your own sales history. Look at sales by SKU over time, then adjust for:
- Seasonality and key trading periods.
- Planned promotions and marketing campaigns.
- Trends, such as products growing or declining.
- New products, using similar items as a guide.
Forecasts will never be perfect. The aim is to be roughly right and review often.
Reorder points and safety stock
A reorder point tells you when to buy more. A simple version is:
Reorder point = (average daily sales × supplier lead time in days) + safety stock
Safety stock is the buffer that covers unexpected demand or late deliveries. Hold more for best-sellers with unreliable suppliers and less for slow-moving or easily replaced items.
Prioritising with ABC analysis
Not every product deserves the same attention. Group SKUs by their contribution to revenue or profit: A items are the few products that drive most of your sales, B items are moderate and C items are the long tail. Monitor A items closely and count them often, and question whether every C item earns its place.
Selling across multiple channels
When you sell on your own store and marketplaces, one stock pool feeds every channel. Use inventory or order management software that updates stock levels across all channels automatically, and consider holding back a small buffer on fast sellers to avoid overselling during busy periods.
Keeping counts accurate
Rather than shutting down for an annual stocktake, use cycle counting: count a small number of locations every day or week, prioritising high-value and fast-moving items. Investigate differences straight away, as they usually point to a process problem such as mis-picks or unrecorded returns.
Key metrics
- Stock turnover: how many times you sell through your average stock in a year.
- Days of cover: how long current stock will last at current sales.
- Stockout rate: how often best-sellers are unavailable.
- Sell-through rate: the share of stock received that has sold.
- Inventory accuracy: how closely system counts match physical counts.
Accurate inventory feeds everything else. See Order Processing & Management for turning stock into shipped orders, and Marketplace Management for syncing stock across channels.
Part of: Operations & Fulfillment