Available is not on-hand: reserved vs. sellable stock
The most dangerous number in any inventory system is the one that says “you have 10”. Ten where? And promised to whom? If 8 of them are booked for a customer who paid a deposit and is waiting for delivery, what you actually have to sell is 2. A salesperson who sees 10 will sell 10, and on delivery day somebody phones a customer to apologise. The gap between those two numbers is not a detail — it is the difference between a promise you can keep and one you cannot.
The idea in a minute
A reservation does not take goods out of the warehouse — they stay exactly where they are, they are simply promised to someone. So the physical balance does not change; what changes is what is available to anybody else.
How it works
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1. A booking holds goods without removing them
When you raise a sales order for a customer, the quantities are reserved. The goods remain in the warehouse — a stock count will find them and valuation still counts them — but they are now tied to that order. There is no stock movement and no accounting entry, because no sale has happened yet.
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2. Three numbers on every item
On the stock balances page every item shows its total, what is reserved from it, and what is available — and per warehouse, not one blended number. Because 10 units in one branch do not help a customer at another, and if all 8 reserved units sit in the same warehouse, that warehouse is effectively empty.
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3. “Out of stock” and “low stock” judge the available number
This is the part that changes behaviour: the shortage tabs in Zemam judge the available number, not the total. An item with 10 units all of them booked counts as out of stock — and that is correct, because none of it can go to a new customer. Had the alert run on the total, you would keep seeing the item as in stock until a customer asked for it and you found out otherwise.
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4. You see availability while picking the item
In the item picker on an invoice, every item carries its available quantity as the headline figure with reserved and total underneath — before you even select it. The salesperson decides while looking at the truth, instead of filling a line and being refused at confirmation.
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5. The system refuses to sell what is booked for someone else
At invoice confirmation Zemam computes what is available (on-hand minus reserved) and compares it to what is being sold. If the sale is bigger, confirmation is refused and the message tells you the available and the required figures by number. So a reservation is not a note on a screen — it is a rule enforced at the moment of sale.
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6. Backorders are allowed — and visible
You can take an order for more than you hold, because that happens every day: the customer orders and the goods are on the next shipment. Zemam records the reservation even when it exceeds the balance, and the gap shows up as a clear shortfall — so you know exactly what to buy instead of discovering the shortage on delivery day.
In short
Available = on-hand − reserved. That is the only number you can promise a new customer.
A reservation moves no stock and posts no entries — the goods stay put, simply spoken for.
Shortage alerts run on the available figure, so an item that is fully booked never looks “in stock”.
Every hold shows its order, customer and requested delivery date — not just a reserved number.
Situations that happen every day
A customer paid a deposit
An order with a deposit is a commitment. The reservation guarantees nobody else sells those goods, and they stay tied to the order until delivery.
Two salespeople working at once
Two people sell the same item in the same minute. The first reserves, the second immediately sees a smaller available figure — instead of both promising and one of them being wrong.
Goods not in yet
You can take the order and book it even when the balance is short. The shortfall shows, and turns into a clear purchasing list instead of guesswork.
The order is cancelled
When an order is cancelled or fulfilled, the hold is released and the goods become available to everyone again automatically — with nobody having to remember to clear it by hand.
Related reading
Promising customers stock you are not sure of?
Talk to us and we'll show you total, reserved and available on your own items — and how the system stops the same unit being sold twice.