Managing stock across sales channels: selling what you don't have is worse than not selling

A small shop making custom motorcycle parts works out of a ground-floor shophouse. There's a display case at the front and a lathe at the back. The owner machines every part himself and sells over the counter, on his Facebook page, on Shopee and on the shop's own website.

On Saturday morning a regular drops in and buys the last pump guard in the case. He pays cash and takes it with him. The owner smiles and goes back to the lathe.

At 9 pm, an order for the same pump guard comes in on Shopee. The listing still says one in stock, because nobody changed it. The customer has paid and is waiting. Two days later he gets a message saying the shop has cancelled.

He leaves one star and writes, "Why list it if you don't have it?" That review is there every time someone new looks at the shop. Almost every shop that sells in several places has been through this, and the lesson is always the same: selling something you don't have is worse than not making the sale.

Overselling costs more than one lost sale

If the listing had said sold out that night, the customer might have followed the shop or asked when more were coming. The shop would have missed one sale, and that's all.

Sell it and then cancel, and the shop loses several things at once. It loses that customer, it gains a review every new visitor will see, and it spends time refunding and replying. Many marketplaces also count seller cancellations against the shop, which can affect how visible it is in the app.

Some imaginary maths: a shop that oversells four times a month gives 48 people a year the worst experience it can offer, paying and getting nothing. To someone choosing where to buy, a small shop that never cancels looks better than a bigger one that cancels often.

Stock drifts because every channel counts the same pile

The problem isn't the owner's memory. It's that the five items in the case get counted as five in every channel at once. Shopee thinks there are five. The website thinks there are five. The Facebook page doesn't count at all because sales happen in chat, and the counter sells without telling anyone.

When sales are slow, the gap hardly matters, because the owner usually updates the numbers in time. But the busiest day is the day he forgets, and the last item usually goes on exactly that kind of day.

Keep the real stock number in one place and let the rest follow it

Shops that rarely oversell tend to have one rule everyone knows. The real number lives in one place only. It might be the website's back office, or even a spreadsheet on a phone. Whichever way an item leaves the shop, that number gets updated first, then the other channels are brought in line.

Your own online store makes a good home for that number, because you control all of it. When customers order on the site, stock goes down by itself. When something sells over the counter or in chat, you update the same place, then refresh the marketplaces on a schedule. If you don't have a store yet, start with starting your own online store.

Some high-volume shops use software that syncs stock with marketplaces automatically, which helps a lot. The rule still applies, though. There has to be one place everyone trusts as the real number.