The point of stock tracking is not a perfect number. It is finding out that the cold drinks are nearly finished before a customer tells you.
Set a low stock level
Each item carries a low stock level, the quantity at which you want warning. Set it to how much you sell while a new delivery is on its way: if you sell two cases a week and your supplier takes three days, warn yourself at one case, not at two bottles.
Reading the stock screen
Every item shows a gauge rather than a bare number, with a tick at its alert level, so you see at a glance whether something is comfortable, getting low or urgent. Filter chips narrow the list to what needs restocking, or what is expiring, which turns a thousand-line catalog into a short shopping list.
Keeping it true
Stock moves on its own in three places. Selling a linked item deducts it. Receiving a purchase order adds it. A free item deducts it, which is why giveaways should be recorded as free of charge and not as a sale at zero.
What stock tracking cannot see is spillage, breakage and the bottle someone took home. That gap is normal, and the fix is a count, not a bigger spreadsheet. See physical stock counts.
Expiry
Grocery items can carry an expiry date, and the stock screen will surface what is close to it. Finding that two days early is the difference between a discount and a loss.
What to track
Track what you buy as units and sell as units: bottles, packets, cigarettes, sacks. For cooked food, track the ingredients you reorder, not every plate.