Data guide
Why tank levels and pump totals differ
Compare like-for-like records before deciding what a stock difference means.
01Keep book stock and measured stock distinct
Book stock is a calculated balance. Measured stock comes from the tank gauge. A delivery entry and a detected change in tank level are different records and should be checked together.
02Use a common period
Start with an agreed opening balance, add recorded deliveries and subtract recorded fuel issues. Compare the result with a gauge reading at the same closing time. Check timestamps, missing uploads and any authorised adjustments.
03A worked example
Opening stock of 10,000 litres plus a 5,000-litre delivery minus 3,000 litres issued gives 12,000 litres of calculated stock. If the corresponding measured stock is 11,900 litres, measured minus calculated stock is −100 litres. This illustration does not establish a fault or an acceptable tolerance.
04Find the cause before adjusting the balance
Check delivery entries, meter and gauge calibration, tank configuration, other outlets and the period covered. Consistent differences may need a different investigation from isolated changes. Record the reason and authority for an adjustment.
05Keep the costing record defensible
Delivery quantities and costs affect stock costing. Correcting a gauge setting does not automatically correct an incorrect purchase entry. Keep an audit trail of corrections and agree which record is used for each management report.
Practical guidance
Document a stock correction without losing its basis
Investigate the difference before deciding which balance should be used operationally.
| Record | Why it matters |
|---|---|
| Original figures | Retain calculated stock, gauge reading and their timestamps before adjustment. |
| Evidence | Check deliveries, issues, other outlets, tank configuration and measurement conditions. |
| Decision | Record the accepted figure, reason, authoriser and effective time; keep the original values available. |
| Costing and permissions | Agree how an adjustment affects valuation and reporting. Confirm the available FMO controls and access permissions for your installation before changing records. |
For example, a 12,000-litre book balance and an 11,850-litre gauge reading create a 150-litre difference to investigate. They do not automatically justify a write-off or establish which figure is correct.
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