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Overselling: why you sell a product that has run out, and how to prevent it

· 4 minute read

Overselling is an order for a product you no longer have in stock. The customer has paid, the product isn’t there, and someone has to call, apologize and refund the money. When you sell on one site it’s rare. When you sell the same products in several stores, it happens every time the stores don’t know about each other.

Where it comes from

  • Each store keeps its own stock, and a sale in one doesn’t lower the quantity in the other.
  • A manual update that comes late, or never comes at all.
  • The last unit sells in two stores a few minutes apart.
  • A different quantity in each store, so one of them shows more than you have in the warehouse.

Sync closes most of the gap

When the stores are synced, a sale in one reaches the others within about a minute. “Out of stock” carries over too: a store that marks a product out of stock and a store that only counts a quantity and reaches zero are treated as the same thing, and the system sees no difference between them. We cover how this works in practice in the article on syncing stock between WooCommerce and Shopify.

If you also have a Wolt venue, an order accepted there lowers the stock on your sites, and a cancellation returns it. A size that runs out on the sites closes on the venue within about 15 minutes.

The Today list on the Overview screen: sales and the updates that followed them
The Today list: every sale, and every update it led to in the other stores. Sample data.

What’s left: the minute between two sales

A sync of about a minute narrows the window, but doesn’t close it entirely. When one or two units are left and two stores sell in the same minute, you can still sell more than you have. That’s what a safety buffer is for: a few units the store doesn’t show, so the last unit stays held back. When it pays off and how to choose its size is in the article on safety buffers.

Quantities that don’t match

The quietest source of overselling is a quantity that was wrong from the start. StoreDuet doesn’t guess: an item whose quantity differs between the stores is marked “Quantity differs”, counted in the “Waiting to be lined up” tile on the Overview screen, and isn’t synced until you set one quantity for it.

The Inventory screen filtered to items whose quantity differs between the stores
Clicking the tile opens the inventory with the items that need settling.

Updates are checked after they’re sent

Sending a quantity to a store is half the job. The other half is making sure it took. Every update the system sends is read back from the store, and counts as done only if the store returns exactly what we asked for. An update that didn’t go through appears in the activity log with the reason, so you see it before it turns into a problem order.

The activity log: every change sent to the stores, and whether it worked
The activity log: every change sent to the stores, what it was before and after, and whether it worked. Sample data.

A short checklist against overselling

  1. Connect every place that sells from the same stock, including a Wolt venue.
  2. Make sure every product and every variation has a SKU.
  3. Settle quantity differences before you turn the sync on.
  4. Give a safety buffer to the store where orders come in fast.
  5. Look at the activity log when something seems wrong.

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