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Excel .xlsx, no email and no sign-up. Every derived cell is a real formula rather than a number somebody typed.
Download monthly stock register
- One sheet per tank, 31 days, opening carried from yesterday's dip
- Book stock, variance and variance as a share of throughput, all computed
- Summary — every tank side by side, because a total hides a drifting one
The format is argued for in the stock register format.
A month per tank, not a month per fuel
This is the decision the whole format rests on. A leak, a drifting nozzle and a decantation shortfall are all properties of one tank, and a register that pools two tanks selling the same grade averages them against each other.
The arithmetic is unkind about it: a tank losing steadily and a tank behaving perfectly, added together, produce a variance that looks unremarkable for months. Kept apart, the drifting one stands out within weeks. The same applies to a branded premium grade, which needs its own tank and its own sheet.
A variance is meaningless as a figure and diagnostic as a series
One day's variance tells you almost nothing — dips are not that precise, and temperature moves the number on its own. Thirty of them in a column tell you a great deal.
A variance that scatters either side of zero is measurement noise. One that sits consistently negative is loss, and its size against throughput says roughly what kind. One that jumps on a particular day points at that day rather than at the tank. That is why the sheet computes variance as a share of throughput beside the litres: the percentage is what makes one tank comparable with another and one month with the last.
- Opening stock is carried from yesterday's dip, not yesterday's book stock — the formula does it, so the error cannot accumulate quietly.
- The summary sheet puts every tank side by side, because a site total hides the one tank that is drifting.
- Deliveries are entered against the tank that received them, which is the only way book stock can mean anything.