You ran a flash sale. 50 people added your limited-edition product to cart at the same time. You had 10 units. WooCommerce sold 47 of them.
Now you’re emailing 37 customers to explain their order can’t be fulfilled. Some want refunds. Some want to know why you advertised something you didn’t have. Your support inbox is on fire.
This is overselling.
The fix: Reserve stock when products enter carts, not when orders are placed. Reserved Stock Pro does this automatically.
Keep reading if you want to understand why this happens and what else you can do.
The Solution: Reserve Stock at Cart
With WooCommerce defaults, stock only decreases when an order is placed. Ten people can have your last item in their carts simultaneously. When they all checkout, you’re oversold.
Cart-level reservation fixes this:
- Customer A adds product to cart. Stock drops to 9.
- Customer B adds to cart. Stock drops to 8.
- When stock hits 0, the next customer sees “Out of Stock.”
- If Customer A abandons their cart, stock releases back after a timeout.
No race condition. No overselling. Customers see real availability.
How Reserved Stock Pro Works
Real-time stock reduction. Stock decreases when added to cart, not at checkout. Other customers see accurate availability.
Visible countdown. Customers see how long their reservation lasts. Creates urgency: “Your cart is reserved for 14:32.”
Automatic release. Cart expires without purchase? Reserved stock returns to inventory. No manual cleanup.
Variation support. Works with variable products. Each size and color reserves independently.
This is how ticket sites and airlines handle scarcity. Stock reserved at intent, not at transaction.
Why WooCommerce Oversells
WooCommerce tracks stock at the order level, not the cart level. Here’s what happens during high traffic:
- Customer A adds your product to cart. Stock shows 10.
- Customer B adds the same product. Stock still shows 10.
- Customers C through J all add it. Stock still shows 10.
- All 10 hit “Place Order” within seconds.
- WooCommerce processes each order: 10, 9, 8… 0, -1, -2…
You’ve sold 10 units you don’t have. Stock wasn’t reserved when products entered carts—only when orders were placed.
This is a race condition. Multiple checkout requests compete for the same stock without coordination. The more popular your product, the worse it gets. Flash sales, Black Friday, viral moments—exactly when you need accurate inventory, WooCommerce fails.
What WooCommerce’s Built-in Settings Can’t Do
WooCommerce → Settings → Products → Inventory has several stock options. None of them reserve stock at cart.
Hold stock (minutes). Holds stock for unpaid orders—customers who started checkout but didn’t pay. Default: 60 minutes. Problem: This kicks in at checkout, after the race condition already happened.
Low stock threshold. Email notifications when stock drops. Useful for reordering, useless for preventing overselling.
Out of stock visibility. Hides products at zero stock. Doesn’t prevent negative stock.
If 20 people have your product in their carts, WooCommerce shows it as available to all 20. Built-in settings can’t change this.
Complementary Protections
Cart-level reservation is the fix. These help too:
Limit Quantities Per Customer
If one customer can buy 10 units, fewer customers get any before you sell out. Min/Max Quantities lets you cap quantity per order.
Prevents bulk abuse and resellers. Doesn’t prevent the race condition—50 people wanting 1 unit each will still oversell if you have 10—but reduces blast radius.
Shorter Hold Stock Time
WooCommerce → Settings → Products → Inventory. Change “Hold stock” from 60 to 15-30 minutes. Releases unpaid checkout stock faster.
Helps with abandoned checkouts. Doesn’t help when 20 people add to cart and checkout within minutes.
Verify Inventory Before Sales
Stock Editor lets you audit stock levels quickly before a sale. Fix discrepancies. Start with accurate numbers.
Combining Protections for High-Traffic Events
For serious sales, layer multiple protections:
| Protection | What It Solves |
|---|---|
| Reserved Stock Pro | Race condition—stock reserved at cart |
| Min/Max Quantities | Bulk abuse—no single buyer wipes inventory |
| Stock Editor | Bad data—verify inventory before sale |
Accurate starting inventory → reserved at cart → protected from abuse → urgency to convert.
Before Your Next Sale
Overselling doesn’t just lose sales—it loses customers. The person who got a cancellation email after ordering your limited product isn’t coming back. They’ll tell their friends. They’ll leave a review.
WooCommerce assumes orderly, sequential purchases. Real commerce isn’t orderly. Reserve stock at cart, not at checkout.