Your inventory decides how much you sell
You can have the best product and the best campaign, but if your inventory isn't well controlled you lose sales two ways at once: you run out of stock right when demand spikes, or you sell what you no longer have and end up cancelling. Both hurt, and both come from the same root: not knowing exactly how much product you have available.
Inventory control is, in plain terms, keeping that count always up to date. It sounds obvious, but it's where most brands trip as they grow. Here are the concepts you need and how to avoid the costly mistakes.
Available isn't the same as "in the warehouse"
The most common mental mistake is confusing two numbers:
- Physical stock: what's in the warehouse right now.
- Committed stock: what's already sold but hasn't shipped yet (paid orders, in preparation).
- Available stock: what you can truly sell = physical − committed.
If you sell against physical instead of available, you oversell. Overselling means promising product that was already set aside for another order. It's the #1 cause of cancellations and bad reviews in ecommerce, and you avoid it by tracking available, not physical.
The numbers worth watching
You don't need a logistics degree, just four figures:
| Concept | What it tells you |
|---|---|
| Available stock | How much you can sell today without overselling |
| Days of inventory | How many days your stock lasts at the current sales pace |
| Reorder point | The level at which you must buy again to avoid stocking out |
| Inventory accuracy | How often the system matches reality |
The reorder point is the most practical one: it's the stock level at which you should already place the order with your supplier, accounting for how long it takes to arrive. If your product restocks in 30 days and you sell 10 a day, your reorder point can't be below 300 units, or you'll run out before the new batch lands.
How to keep the count reliable
Three practices keep inventory in order:
- Cycle counting. Count a slice of the warehouse every week on rotation, instead of one massive annual count. It catches small discrepancies before they become a problem.
- Channel sync. Have your stock decremented automatically in Shopify, Mercado Libre or Amazon the moment an order comes in. If you update by hand, overselling is only a matter of time.
- One system, one source of truth. Let a single system keep the count —not a spreadsheet per channel— and let you see it in real time.
This is where an external operator helps most: a good warehousing service does the cycle counting for you, keeps available stock synced with your stores, and gives you the right number without you chasing it. And when an order comes in, that same inventory feeds your fulfillment directly, with no double entry.
Frequently asked questions
What is overselling and how do I avoid it?
It's selling more units than you actually have available. You avoid it by selling against available stock (physical minus committed) and syncing your inventory across all channels in real time.
How often should I count my inventory?
Ideally never "all at once": with cycle counting you count a portion every week, on rotation. That way you always have a recent picture without freezing the operation.
Is a spreadsheet enough?
At first, yes; as you grow, no. The moment you sell on more than one channel or move volume, the spreadsheet drifts and overselling appears. That's when a system that auto-decrements pays off. More on this in How warehousing works.
Is inventory control part of warehousing or fulfillment?
It lives in warehousing (that's where product is counted and stored), but it feeds fulfillment (which pulls from it to prepare orders). That's why it helps to have one operator for both. See Storage vs. Fulfillment.
Tired of cancelling orders over miscounted inventory? See Ecommex's warehousing service — available stock synced with your stores, cycle counting and real-time inventory visibility.