BSFC Calculator Inputs
Enter direct brake power, or leave it blank and derive power from torque and RPM.
Example Data Table
| Scenario | Fuel Type | Fuel Flow | Brake Power | BSFC | Efficiency |
|---|---|---|---|---|---|
| Compact diesel generator | Diesel | 12 kg/h | 45 kW | 266.67 g/kWh | 31.62% |
| Medium-duty engine cruise | Diesel | 18 kg/h | 70 kW | 257.14 g/kWh | 32.81% |
| Small gasoline engine | Gasoline | 9 kg/h | 32 kW | 281.25 g/kWh | 29.09% |
Formula Used
BSFC = Fuel mass flow rate ÷ Brake power
BSFC (g/kWh) = Fuel flow (kg/h) × 1000 ÷ Brake power (kW)
Power (kW) = Torque (N·m) × RPM ÷ 9549.3
Efficiency (%) = Brake power (kW) ÷ [Fuel flow (kg/s) × LHV (MJ/kg) × 1000] × 100
BSFC tells you how much fuel mass an engine needs to produce one kilowatt-hour of useful brake output. Lower values usually indicate better fuel economy at the measured operating condition.
How to Use This Calculator
- Enter the fuel flow rate and choose its unit.
- Select the fuel type, or choose custom and enter your own density and heating value.
- Enter brake power directly, or leave it blank and provide torque with RPM.
- Add operating hours to estimate total fuel usage over a trip or run.
- Enter price per liter if you want a fuel cost estimate.
- Click Calculate BSFC to show the result above the form.
- Use the CSV or PDF buttons to save the report.
Frequently Asked Questions
1) What does BSFC mean?
BSFC stands for brake specific fuel consumption. It measures how much fuel mass an engine uses to produce one unit of brake power over time.
2) Is a lower BSFC better?
Yes. A lower BSFC usually means the engine converts fuel into useful output more efficiently at that operating point.
3) Why can I enter torque and RPM?
Torque and RPM can be used to calculate brake power. That helps when dyno or engine data gives torque but not direct power.
4) Why does fuel density matter?
Density is needed when fuel flow is entered by volume, such as liters per hour or gallons per hour. The calculator converts volume flow to mass flow first.
5) What is lower heating value?
Lower heating value is the usable chemical energy released by the fuel per kilogram, excluding latent heat from water vapor condensation.
6) Can I use this for generators and boats?
Yes. BSFC works for engines in cars, boats, generators, tractors, and other machines, as long as fuel flow and output power are known.
7) Does BSFC change with load?
Yes. Engines usually have a more efficient load range. Very light or very heavy loading often increases BSFC.
8) Can this help estimate trip fuel cost?
Yes. Enter operating hours and fuel price per liter. The calculator estimates total fuel volume and cost for that duration.