Inventory in a System vs a Spreadsheet: When a Sheet Is Still Enough

An inventory spreadsheet is fine as long as one person updates it and every quantity change comes from an action that person performed. It starts costing money the moment more than one person touches stock, because then there is no document behind the change - and a gap found at the stock count can no longer be explained.

Five practical tests

1. How many people change a quantity in a month. More than one is a risk.
2. What happens to a return that arrives on a Friday. If the answer is "someone will remember", that is a risk.
3. How long it takes to answer how many units of an item you hold. Over a minute means the number is not managed.
4. Is there a document behind every quantity change. If not, there is no source of truth.
5. How large was the gap at the last count, and when did it appear. No answer to the second half is the test you failed.

A business that passes all five can stay on a spreadsheet with a clear conscience. One that fails three or more is already paying for it, just not under a line called "inventory".

What a spreadsheet does well

• Fast to set up with no implementation.
• Completely flexible - a new column in a second.
• Understood by everyone without training.
• Cheap, including to maintain.

Which makes it the right tool for a business with small, stable stock, for the first season of a new product, and for non-critical stock - consumables, packaging, office supplies.

What breaks an inventory spreadsheet

The last row is the critical one: in a movement-based system a gap leads to an investigation - which movement is missing, when, who performed it. In a spreadsheet a gap leads only to a correction, which is why it recurs.

What does an inventory system actually give you?

Not "more fields". Three substantive things: a recorded movement behind every quantity change, so you can trace backwards; a link to a document - a goods receipt, delivery note, purchase order - so that quantity and money agree; and controls such as minimum reorder levels that warn you before you run out.

Rivhit, for example, presents an inventory module with movement tracking around purchasing and sales, warehouse management and minimum-quantity controls. A full ERP adds bills of materials, batches and costing - and the difference between the two is covered in Priority versus Rivhit.

The intermediate step that saves money

Before buying a system, much of the benefit is available in one spreadsheet: stop editing the quantity and start recording movements. Instead of a "quantity" column somebody overwrites, keep a row per movement - date, item, quantity plus or minus, reason, who recorded it - and derive the quantity from the sum.

It sounds like more work and is almost the same effort: the person who wrote "12" now writes "minus 3, sale, June". What changes is that a gap can be investigated, and that a later move to a system becomes simple - because the data is already in the right shape.

When not to wait

There are three situations where deferring costs more than it saves: stock in several locations, because the sheet represents one reality and there are two; production or assembly, because materials stock and finished stock depend on each other; and stock being the largest asset in the business, because then a few per cent of discrepancy is a meaningful sum.

In every other case, a deliberate decision to defer is entirely reasonable - provided it is revisited once a year rather than forgotten until the next count reveals a large gap.

What does a stock discrepancy really cost?

The first cost is visible: goods that are not there. The second is usually larger - a sale not closed because the system said there was none when there was. The third is the reverse and does the most reputational damage: a promise made to a customer on a wrong quantity, followed by an awkward conversation about a delay.

There is a quiet fourth cost: unnecessary purchasing. When nobody trusts the number, people order "to be safe", and the money sits on a shelf. In businesses with large stock this is often the biggest expense flowing directly from poor inventory management, and it is almost never attributed to it, because it looks like a reasonable purchasing decision.

What to define on day one, in any tool

Whether in a spreadsheet or a system, four definitions decide whether the number is trustworthy:

• One unit of measure per item. An item bought by the case and sold by the unit needs a defined conversion, not an estimate.
• Who may change a quantity, and what is required to do so - a document, an approval, or nothing.
• How a return is recorded - the case that trips up every business that did not define it in advance.
• When you count - a fixed frequency, not "when something feels off".

The third produces most discrepancies in small businesses, and it is cheap to fix: a two-line procedure on the warehouse wall is worth more than an expensive module nobody updates.

Sources

• Rivhit - inventory management module
• Priority Software