Convert specific fuel consumption (g/kWh) to liters per hour, kg/h and gallons/h — for diesel, gasoline, LPG, biodiesel and more
Density: 830 g/L
Typical SFC (g/kWh)
Engine size
Fuel consumption
Q = 220 × 100 / 830 = 26.51 L/h
Total fuel for a run
History
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Typical specific fuel consumption by engine type
Engine
SFC (g/kWh)
Efficiency
Low-speed marine diesel (2-stroke)
165–175
~50%
Modern automotive diesel
195–220
~40%
Diesel generator set
210–250
~36%
Industrial gasoline engine
270–320
~28%
Small 2-stroke gasoline
350–500
~18%
Industrial gas turbine
200–280
~33%
Frequently asked questions
SFC is the mass of fuel an engine burns to produce one kilowatt-hour of mechanical work, expressed in grams per kWh. Lower SFC means a more efficient engine. A modern automotive diesel runs at 195–220 g/kWh, while a 2-stroke marine diesel can reach 165 g/kWh. Multiplying SFC by power output and dividing by fuel density gives the volumetric flow in liters per hour.
Use the formula Q = SFC × P / ρ, where Q is liters per hour, SFC is in g/kWh, P is engine power in kW, and ρ is fuel density in g/L. Example: a 100 kW diesel at 220 g/kWh and density 830 g/L burns 220 × 100 / 830 ≈ 26.5 L/h. Pick the fuel from the dropdown above and the calculator handles the density automatically.
Specific fuel consumption is a mass figure (grams), but engines and tanks are usually measured in liters. Different fuels have very different densities: diesel is 830 g/L, gasoline 745 g/L, LPG only 500 g/L, and HFO 960 g/L. The same SFC therefore translates into different volumetric flows. For example, 200 g/kWh on diesel is 0.241 L/kWh, but on LPG it is 0.400 L/kWh.
Run the engine close to its sweet-spot load (typically 70–85% of rated power), keep injectors and air filters clean, maintain the correct turbo boost and intercooler temperature, use the recommended fuel grade, and avoid long idling. On generators, sizing the unit so it operates above 50% load makes the biggest difference: a 200 kW genset loaded at 30 kW often burns more fuel per kWh than the same engine loaded at 150 kW.
1 mechanical horsepower (hp) equals 0.7457 kW. So 100 hp ≈ 74.6 kW and 1000 hp ≈ 745.7 kW. Switch the power unit dropdown to "hp" in the calculator and it will handle the conversion automatically. Note that some manufacturers use metric horsepower (PS / CV), where 1 PS = 0.7355 kW — the difference is small (about 1.4%) but worth checking on European spec sheets.
BSFC (Brake Specific Fuel Consumption) is SFC measured at the engine output shaft, i.e. brake power. It is the value most commonly published on engine datasheets and is what this calculator expects. ISFC (Indicated SFC) is measured from in-cylinder pressure and is always lower than BSFC because it does not include mechanical losses. If your datasheet just says "g/kWh" without qualification, it almost always means BSFC.
Results are theoretical and based on steady-state operation at the given specific fuel consumption. Actual fuel use depends on load profile, ambient conditions and engine wear. Verify against manufacturer data before sizing tanks or budgeting fuel.
About this fuel consumption calculator
The calculator converts specific fuel consumption (g/kWh) into volumetric flow rate for diesel, gasoline, LPG, biodiesel, ethanol, heavy fuel oil and natural gas, accounting for engine power and fuel density. Switch the power input between kilowatts and horsepower, choose a fuel preset or enter a custom density in g/L, then read the result in L/h, kg/h and US gallons per hour. The reverse mode (L/h to g/kWh) lets you derive the actual specific consumption from a measured flow.
Worked example
A 100 kW automotive diesel engine running at 220 g/kWh on standard diesel (density 830 g/L) burns: Q = 220 × 100 / 830 ≈ 26.5 L/h. Over an 8-hour shift that is 212 L of fuel, or about 56 US gallons. The built-in efficiency scale shows where the engine sits between best-in-class marine diesels (~165 g/kWh) and small low-efficiency petrol units (~400 g/kWh).