How to calculate it
Stock loss is the difference between what the records say should be in a tank and what the dip says is there:
| Book stock | Opening dip stock + tanker receipts − meter sales + test fuel returned |
| Physical stock | Closing dip, converted with the calibration chart |
| Gain / loss | Physical − book |
| Loss % | Loss ÷ meter sales × 100 |
Try it with your own figures in the stock loss calculator.
Normal causes
- Evaporation. Petrol in particular evaporates, more so in heat and during decantation.
- Temperature. Fuel expands when it warms and contracts when it cools, so a dip in the morning and one in the afternoon measure the same fuel differently. Over a month these swings largely cancel out.
Oil companies set permissible limits for stock variation, which differ for petrol and diesel. Compare your monthly figure with the limit in your OMC's current guidelines.
Causes that need action
| Sign | Likely cause |
|---|---|
| Loss appears on the day of a delivery | Tanker delivered short — check dips before and after decanting |
| Loss on one product only, growing slowly | A dispenser meter running slow, or a leak |
| Gain that keeps recurring | A meter running fast — customers are being short-delivered |
| Sudden one-day jump | A dip misread, the wrong chart, or a sale not entered |
| Steady loss that nothing explains | Possible leak in the tank or pipeline — get it tested |
How to keep it under control
- Reconcile every tank every day, not at month end.
- Check density and dip before and after every decantation.
- Record test fuel, and return it to stock if it goes back into the tank.
- Keep fill caps and dip pipes closed and sealed.
- Watch the trend: a slowly growing loss is a meter or a leak.
Maxify reconciles every tank against its dip night after night and alerts you when the variance passes your tolerance. On the Intelligence plan, Loss Radar also corrects for temperature and flags challan shortages and meter drift. See Loss Radar.
Frequently asked questions
Is a stock gain a good thing?
No. A recurring gain usually means a meter is delivering less than it shows, which short-changes customers and is a Legal Metrology risk.
What is the permissible evaporation loss for petrol?
It is set by your oil company and differs between products. Use the figure in your OMC's current guidelines rather than a number from the internet.