Diesel usage logbook
Record diesel received and used per vehicle or machine, with totals by activity, ready to print.
Enter the opening stock, then add deliveries and fills. The tank balance, consumption and totals appear as you go.
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Diesel logbook
Printed
Bulk tank
| Date | Entry | Supplier or vehicle | Invoice | In (L) | Out (L) | R/L | Balance (L) | Actions |
|---|---|---|---|---|---|---|---|---|
| Opening stock | 0 | |||||||
| Expected balance | 0 | 0 | 0 | |||||
Fills
No fills recorded yet.
Totals by vehicle or machine
No vehicles or machines yet.
Totals by activity
No fills recorded yet.
How this is calculated
The logbook keeps two records. Bulk tank: every delivery into your tank (date, supplier, invoice number, litres and, if you have it, the price per litre) and every litre issued out of it, with a running balance. Fills: every time diesel goes into a vehicle or machine, with the date, litres, the odometer (km) or hour-meter reading, the activity, the field or location and the operator.
- Tank balance = opening stock + litres received − litres issued, worked out after each entry in date order. On the same day, deliveries are posted before fills.
- Consumption assumes you fill to full each time, so the litres put in at a reading are what was used since the last reading. Tractors, harvesters, pumps and generators use litres per hour: 96 L at 1 208 h after a fill at 1 200 h is 96 ÷ 8 = 12 L/h. Bakkies and trucks use litres per 100 km: 54 L at 45 650 km after 45 200 km is 54 ÷ 450 × 100 = 12 L/100 km.
- A fill with no meter reading has no figure of its own; its litres are added to the next interval, so 40 L unread and then 30 L at 110 h after 100 h is 70 ÷ 10 = 7 L/h. A reading the same as the one before also gives no figure and its litres go to the next interval. The first reading for a machine only sets the starting point. A reading lower than the one before (a typing slip, or a new meter) gives no figure and the count restarts from it. Litres filled before a first or restarted reading have no known starting point, so they count in the tank and totals but not in consumption.
- Average consumption per machine = all litres in valid intervals ÷ all km or hours in them, not an average of the individual figures, so a short interval doesn't skew it.
- Cost = litres × the average price paid, weighted by litres across the deliveries that have a price. 1 000 L at R20.00 and 3 000 L at R22.00 average R21.50/L.
- Reconciliation: dip the tank and enter the reading. Variance = dip − expected balance, and as a percentage of the expected balance. 500 L opening + 2 000 L received − 1 300 L issued = 1 200 L expected; a dip of 1 140 L is 60 L (5%) short.
Small differences come from reading the dipstick and from diesel expanding and contracting with temperature. A shortfall that keeps growing from one dip to the next points to fills that were never written down, a leak or theft. Keep the dip and the book up to date weekly so a problem shows early.
This is a general record for managing fuel. If you claim a diesel refund or rebate, such as South Africa's refund for primary producers, the tax authority sets its own logbook requirements; check them with your accountant and keep your invoices with this record.
Read the guide: Keeping a diesel logbook for every vehicle and machine
Results are estimates for planning. Check product labels and local recommendations before you apply anything.