Generator fuel calculator
How much fuel a generator burns over a shift, and what it costs.
Fill in the fields and the result will appear here automatically.
Estimate fuel for a selected constant load by multiplying kW, specific consumption and operating hours. The retained 0.3 L/(kWh) is an input example, not a universal diesel or petrol rating. Manufacturer data or measured consumption must match your load. An optional price adds the cost of that volume; warm-up and idling need separate data.
How it works
Formula and logic
At constant load P kW and entered specific use s L/(kWh), hourly fuel F=P×s and total fuel F×t for t hours. Price per litre multiplies that volume; blank or 0 omits cost. P,s,t>0 and price≥0. Split changing loads into stages with suitable s; this linear model cannot infer idle fuel from zero electrical load.
Example
A generator under a 5 kW load at 0.3 L/kWh burns 12 litres over eight hours — at 60 per litre that is 720. 0.5 kW×0.4 L/(kWh)×2.5 h gives 0.5 L; price 0 omits cost.
Fields and units
- Load, kW — kW
- Specific consumption, L/kWh — L/kWh
- Running time, h — h
- Fuel price per litre — $
How to use
- — Enter the actual load in kilowatts, not the generator rating.
- — Give the specific consumption from the machine data sheet.
- — Set the running time and, if you need it, the fuel price.
Method and limitations
- Calculation method
- Formula and logic
- Data or methodology source
- Caterpillar 3412, LEHE1468-04 (10/2019): load-specific fuel data for this model; not approval of a universal 0.3
- Limitation
- Split changing loads into stages with suitable s; this linear model cannot infer idle fuel from zero electrical load.
FAQ
Where does the specific consumption come from?
From your machine’s data at the relevant load. If it gives litres per hour, divide by delivered kW to obtain L/(kWh). The retained 0.3 is an example to replace with a suitable value.
Do I enter the load or the rated power?
Actual electrical load, consistent with the specific consumption. The rating states machine capacity, not current output. Idle fuel cannot be inferred from this linear formula.
Why is low load inefficient?
The engine also consumes fuel for its own operation, so L/(kWh) can change with load. The size of the change is machine-specific; use its curve rather than a universal 1.5–2 multiplier.
Are warm-up and idling included?
No. Calculate idling separately using measured litres per hour or manufacturer data. Simply extending hours at the same load does not reproduce a different operating mode and can overstate or understate fuel.