Inventory management is one of the most critical parts of running a reseller business, and one of the easiest to get wrong. Mistakes in this area can cost you sales, frustrate customers, and even damage your reputation on platforms like Amazon and eBay.
The good news? Most of these mistakes are common and completely avoidable. In this post, we’ll go through the top 10 inventory mistakes small resellers make, and how to fix them with real-world examples.
1. Not Updating Inventory in Real Time
If you don’t adjust stock levels as soon as items sell, you risk overselling and canceling orders. Overselling leads to refunds, negative reviews, and lower seller rankings.
Example: A reseller sold a pair of sneakers on eBay, but forgot to remove it from their Mercari listings. When it sold there too, they had to cancel the second order, costing them a bad review.
Fix: Make it a daily habit to update inventory. Better yet, use tools that sync across marketplaces.
2. Relying Only on Memory
Trying to “remember” how many units you have leads to chaos. Once you’re managing more than a handful of SKUs, mental tracking falls apart.
Example: A toy reseller thought they had 6 action figures left but only had 2. They oversold during the holiday rush and missed out on several sales.
Fix: Always track inventory in a spreadsheet or system — even if you only sell 10 products.
3. Overstocking the Wrong Products
Stocking too much of slow movers ties up cash that could be used for profitable flips.
Example: A reseller bought 50 units of a kitchen gadget that took over a year to sell. Meanwhile, they constantly ran out of hot-selling video games.
Fix: Use sales data to identify your top 20% best-sellers and prioritize them for restocking.
4. Ignoring Safety Stock
Running down to zero before reordering = guaranteed stockouts and lost sales.
Example: A reseller selling phone chargers sold out right before back-to-school season. By the time restock arrived, the seasonal spike was gone.
Fix: Set reorder points and maintain safety stock for fast sellers. If your supplier takes 10 days, reorder when you have at least 10–15 days’ worth of stock left.
5. Poor Organization of Storage
If you can’t find items quickly, shipping delays will hurt your ratings. Marketplace algorithms penalize late shipments.
Example: A seller once spent 45 minutes searching for a single book buried in unmarked boxes. The delay caused late shipment and a hit to their eBay rating.
Fix: Label shelves, bins, or boxes clearly. Group products by category, SKU, or supplier.
6. Not Doing Spot-Checks
Small errors pile up into big problems. Without checks, you’ll eventually oversell or miscount.
Example: A reseller discovered $300 worth of “lost” stock during a spot-check. It had been mislabeled and left unsold for months.
Fix: Do weekly spot-checks of 10–15 SKUs. Over time, you’ll cover your full inventory without needing full audits.
7. Forgetting to Track Costs and Fees
If you only track selling prices, you’ll never know your real profit. Marketplaces and shipping fees add up quickly.
Example: A reseller thought they were making $10 profit per sale, but after Amazon fees, shipping, and packaging, it was only $3.
Fix: Always track purchase price, marketplace fees, shipping, and packaging costs. Calculate net profit, not gross.
8. Ignoring Seasonal Demand
Treating all products the same leads to missed opportunities.
Example: A reseller missed Q4 toy sales because they didn’t stock up early enough. By November, prices had doubled on Amazon, and they lost the chance to profit.
Fix: Plan for seasonal spikes like holidays, back-to-school, or summer gear. Review sales from previous years and anticipate demand.
9. Failing to Review Dead Stock
Dead inventory eats storage space and ties up cash flow.
Example: A reseller kept 20 pairs of outdated headphones in storage for over a year, paying monthly storage fees on unsellable stock.
Fix: Review monthly. Discount, bundle, or liquidate items that haven’t sold in 90+ days.
10. Waiting Too Long to Upgrade Systems
Manual tracking works at first but becomes overwhelming as you grow. Once you’re juggling hundreds of SKUs, spreadsheets become error-prone.
Example: A reseller with 300 SKUs was still using Excel. Updating after each sale took hours daily and errors piled up. They eventually switched to inventory software and cut management time by 70%.
Fix: Once you hit 100+ SKUs, start using dedicated inventory tools. They automate tracking and prevent costly errors.
FAQs on Reseller Inventory Mistakes
Q: What’s the #1 inventory mistake new resellers make?
Overselling due to poor tracking. It hurts profits and seller reputation.
Q: How can I prevent dead stock?
Review inventory monthly. If items don’t move in 90 days, consider discounts, bundles, or liquidation.
Q: When should I switch from spreadsheets to software?
When updates start taking too long or errors cost money. Around 100 SKUs is a good threshold.
Final Thoughts
Every reseller makes mistakes, but the key is learning from them quickly. By avoiding these 10 inventory pitfalls, from overselling to ignoring seasonal demand, you’ll save money, protect your seller reputation, and keep your business running smoothly.
Start with one fix today: label your storage area, create a simple spreadsheet, or set reorder points. Small changes can have a big impact on sales and efficiency.