In short
Stock from a weighbridge is computed per material: total inbound net minus total outbound net, from finalized tickets only, scoped to the branch. A gap against a physical count may be normal, such as moisture and handling loss, or a warning, such as a ticket never recorded.
The principle is deceptively simple: inbound adds, outbound subtracts, and the difference is your balance. But compare that balance to a physical count and a gap appears — and the question that occupies site owners is where it came from, not the arithmetic.
Some of that gap is normal and cannot be removed. Some of it is a warning. The skill is telling them apart.
The calculation itself
Per material: total inbound net − total outbound net, taken from finalized tickets only, and scoped to the branch if you run more than one site. The three qualifiers in that sentence are exactly what usually goes wrong:
- Per material — not a grand total. A grand total tells you nothing you can act on.
- Finalized only — pending and cancelled tickets stay out of the calculation.
- Scoped to the branch — otherwise two sites blend into one figure that describes neither.
Normal gaps — do not chase these
Moisture
Sand, grain and organic waste come in at one weight and leave at another because their water content changed. Sand that arrived after rain and left after a week of sun will weigh less — and that difference is real, not loss.
Handling loss
What spills during loading and unloading, and what stays on the floor or in the bottom of the store. A small percentage, but it accumulates, and it varies by material and by how you handle it.
The scale's resolution
Every scale has a division, and every reading is rounded to it. Across thousands of tickets those roundings accumulate one way or the other. The resulting difference is relatively small, but it is not zero.
Gaps that are not normal — these deserve investigation
- Tickets never recorded. Goods left without a ticket. Auditing existing tickets will not find it; only comparing gate movement against weighing will.
- The wrong material on the ticket. The weight is right but booked to another material. The result is a shortfall in one and a surplus in another of roughly the same size — a distinctive signature, and the first thing to look for.
- Unrecorded returns. A load went out, came back, and was entered as new inbound rather than a return, doubling the balance on paper.
- Inter-branch transfers. Left one site and never arrived at the other, so it reads as a shortfall with no counterpart.
- Several names for one material. “Sand” and “Washed sand” split one balance in two, so one looks short and the other looks long.
A negative balance is not an error — it is a message
When a material shows negative, the literal meaning is: more left than the record says arrived. Which means one of three things: inbound never recorded, outbound booked to the wrong material, or an opening balance that was never entered when the system started.
The common mistake is hiding the negative or zeroing it by hand. It should stay visible until its cause is known — it is the clearest indicator you have that recording has broken somewhere.
Closing the gap in practice
- Start from a real opening balance. A physical count on a fixed day becomes your zero. Without it the gap persists forever, however well you run everything after.
- Close the material list. A registered list the operator selects from. This alone resolves a large share of unexplained differences.
- Tie exit to a permit. Unrecorded tickets disappear — the largest source of genuine shortfall.
- Count one or two materials monthly rather than everything annually. Frequent partial counts catch drift while it is small and still explainable.
- Record the usual gap percentage per material. After three months you will know that sand, say, varies within a certain band. Then the signal is leaving the band — not the existence of a gap.
What any system should give you
Showing the balance is not enough. A balance on its own says “there is a problem” without saying where. You need to get from the figure to its source: click a material's balance and see the tickets that built it, with their dates, customers and who recorded them.
That turns stocktake from an annual confrontation into ordinary review — which is the real difference between a system that records and one that helps.