Online and in-store inventory in sync: how to stop selling what you don't have

Synced inventory means your online store and your in-store register pull from the same number. If someone buys the last jacket off the rack, the website stops offering it right then. If someone orders it online at night, the person opening the shop in the morning already knows it's spoken for.

It sounds obvious, but in plenty of shops the website stock and the store stock live in two different spreadsheets that someone reconciles when they get a chance. The day they don't, a customer who already paid gets the worst message possible: “Sorry, that one just sold in the store.”

Why the numbers drift apart

It isn't anybody's fault. Each channel has its own rhythm. The store sells one at a time, fast, with a customer waiting. The website sells at any hour, including when the shop is closed. And in between, there's stuff that isn't a sale but still moves stock: an exchange, a return, a damaged item, a box sent to the other location.

If those get written down somewhere the website doesn't look, sooner or later the numbers stop matching. The problem is rarely the counting. It's having more than one place where counting happens.

What a single, shared inventory needs to handle

It's not enough for both channels to “look at” the same number. There are everyday situations you have to think through ahead of time:

• A counter sale lowers stock when it's rung up, not whenever someone remembers to note it.
• An online order holds the item as soon as it's confirmed, even before it ships, so the store doesn't sell it.
• An unpaid order releases the hold after a time limit you choose, so products don't get stuck.
• Returns and exchanges go back into stock only if the item is sellable; otherwise they're set aside.
• Every adjustment has a reason: damaged, given away, recount. When something doesn't add up, you know where to look.
• Branches and the stockroom are tracked separately, even if the website shows the total or the nearest location.

A safety buffer for fast sellers

Some items move so fast in the store that an online order can sneak in between the register sale and the website update. For those, a buffer helps: when only a few are left, the website shows them as sold out or “ask about availability,” and the last couple are kept for walk-ins.

That's a business decision more than a technical one. Some owners never want to disappoint the person standing at the counter; others feel the opposite. What matters is that you choose the rule and it lives in the system, not in one employee's head.

Two spreadsheets vs one shared inventory

If you also sell on a marketplace or a hosted platform

Lots of shops have a physical store, a Shopify site and listings on a marketplace like Mercado Libre or Amazon. Each keeps its own count, and the owner ends up being the one who reconciles them by hand. Syncing doesn't mean dropping any of them. It means one of them, or your own system, is in charge, and the rest update from it.

Which one should be in charge depends on where you sell most and where it's easiest to manage products. I covered the point-of-sale side in point of sale with inventory control. If you sell mostly wholesale, the logic changes quite a bit; see inventory system for distributors.

How to get started without stopping the business

The order I suggest: first a real count of what you sell online, then the store register drawing from that same stock, and only then the finer rules (holds, buffers, branches). Meanwhile, the shop stays open and the website keeps selling.

Once stock lives in one place, you also get something you weren't looking for: knowing what sells in each channel. That opens the door to sales reports for retail stores that tell you what to reorder and what to stop carrying.

I work remotely from Buenos Aires, Argentina (UTC−3), with video calls and progress you can open from a link, in English or Spanish. I quote each project based on what needs connecting.

Frequently asked questions