Overselling happens when your store accepts an order for an item you no longer have. The buyer has paid or committed, you have nothing to ship, and the next steps are all bad: a cancellation, a refund, an apology and a buyer who may not come back.
Most overselling comes from a few predictable causes, and each has a simple fix. This guide explains how to avoid overselling by keeping stock accurate from the moment an order comes in.
Why overselling happens
Stock counts drift away from reality for a handful of reasons:
- Stock is updated by hand. Someone reduces the count after packing, or at the end of the day. Until then, the store keeps selling the same units.
- Several places sell the same stock. An online store, a physical shop counter and another sales channel all draw from one shelf, but each keeps its own count.
- The count was wrong to begin with. A miscount at delivery, a damaged item still counted, a unit taken for a photo shoot and never recorded.
- Returns and cancellations are not recorded. Items come back to the shelf, or never leave it, without the count changing.
- Stock is in the wrong place. The system says 5 in stock, but they are in a second location that does not ship online orders.
Rule 1: Have one source of truth
Pick one place where the stock number lives, and make every sale and every movement change that number. If the online store has one count, a spreadsheet has another and the shop counter has a third, at least two of them are wrong at any moment.
When you sell through more than one place, decide which system holds the master count and how other sales reach it. If another channel cannot update it automatically, record those sales in the master system at fixed times, for example after every shop shift, and keep a buffer (see Rule 3).
Rule 2: Reduce stock when the order is placed
The safest moment to reduce stock is when the order is placed, not when it is packed or shipped. If stock only changes at packing time, there is a window in which the same unit can be sold again.
Ask of any system you use: is the stock count reduced at the same moment the order is created, as part of the same step? If the answer is "a few minutes later" or "when you mark it shipped", you have a gap.
Rule 3: Use a safety buffer where counts are uncertain
When stock is shared with a channel that updates late, or when counts are often a little off, do not offer every last unit online. Keep a small buffer:
Units to offer online = units on hand − safety buffer
Safety buffer = units that typically sell elsewhere between two updates of your master count
Example: your shop counter sells about 2 units of a popular mug between two updates (example figure). With 10 on hand, you offer 8 online. You may miss an occasional sale, but avoid a cancellation.
Rule 4: Record every movement, not only sales
Accurate stock means recording everything that changes it:
- deliveries from suppliers as restocks, after counting what actually arrived;
- damaged or lost items as adjustments, with a reason;
- items taken for photos, samples or gifts as adjustments;
- moves between locations as transfers, out of one and into the other;
- returns as restocks into the location where the item really goes.
When every change leaves a record, a wrong number can be traced instead of guessed.
Rule 5: Count regularly, a little at a time
Even with good habits, counts drift. A full stocktake once a year is not enough for a busy shop. Cycle counting works better: count a small group of SKUs each week, starting with the fastest sellers and the most expensive items. Inventory Management for Small Business: A Beginner's Guide covers full and cycle counts in more detail.
Count accuracy = SKUs where the count matched ÷ SKUs counted
If accuracy drops, look at the movement history of the wrong SKUs to find the cause. For a big count, pause new orders while you count, so the numbers do not change under your hands.
How a market weekend oversold one candle
Here is an example with made-up numbers. A shop sells a bestselling candle online and at a market stall on weekends. On Friday the online store shows 12 in stock.
- Saturday: 7 candles sell at the stall. The owner updates the master count on Sunday evening.
- Saturday and Sunday: 6 candles sell online.
Total sold: 13, from 12 on hand. One order is oversold.
With a buffer equal to typical weekend stall sales (example: 7), the store would offer only 5 online over the weekend. Combined with an update after each market day, the oversold order would not have happened.
If an order is oversold anyway
- Tell the buyer quickly and honestly, before they ask.
- Offer choices: wait for a restock with a clear date, switch to a similar item, or a full refund.
- Fix the cause: check the movement history for the SKU and correct the habit that caused the gap.
An overselling prevention checklist
- [ ] One master stock count for every SKU.
- [ ] Stock reduced when the order is placed.
- [ ] Sales from other places recorded at fixed times.
- [ ] A safety buffer where counts are shared or uncertain.
- [ ] Every restock, adjustment, transfer and return recorded.
- [ ] Weekly cycle counts of fast sellers.
- [ ] A clear message ready for oversold orders.
Stock and orders in RedCart
In RedCart, stock is kept per warehouse and per SKU in the same shop database as products and orders. When a buyer places an order, stock is written off in the same transaction, so there is no separate step to remember. Storefront orders are sold from the default warehouse.
Every change leaves a record in the movement log: restock, sale, adjustment, transfer in and transfer out. Sales from a counter or another channel can be recorded as adjustments (they then appear in the log as adjustments, not as sales), and accepted returns go back into the warehouse you choose. For a big count, "pause orders until" stops checkout from accepting new orders until the time you set.
Summary
Keep one source of truth, reduce stock when the order is placed, use a buffer where other places sell the same stock, record every movement and count a little every week.
If you would like stock that changes with every order, create a RedCart account.