Fuel Flow Rate Calculator

Enter Fuel System Data

Calculation Method

Choose the engineering method that matches your available data.

Fuel Density (kg/m³)

Typical gasoline is near 720–780. Diesel is often higher.

Fuel Price per Liter

Optional. Used for operating cost estimates.

Currency Code

Examples: USD, EUR, PKR, AED.

Vehicle Speed (km/h)

Optional. Adds L/100 km conversion for moving systems.

Volume and Time Mode

Total Fuel Volume

Volume Unit

Elapsed Time

Time Unit

Mass and Time Mode

Total Fuel Mass

Mass Unit

Elapsed Time

Time Unit

Power, Load, and BSFC Mode

Engine Power

Power Unit

BSFC (g/kWh)

Load Factor (%)

Injector-Based Mode

Number of Injectors

Injector Flow per Injector (cc/min)

Duty Cycle (%)

Rated Injector Pressure (bar)

Actual Rail Pressure (bar)

Example Data Table

These sample scenarios show typical engineering-style inputs and the kind of outputs this calculator can summarize.

Scenario	Method	Input Snapshot	Approx. Flow
Portable generator	Volume and time	18 L over 6 h, density 745 kg/m³	3.000 L/h
Diesel pump skid	Mass and time	54 kg over 3 h, density 830 kg/m³	21.687 L/h
Industrial engine	Power and BSFC	250 kW, 75%, 215 g/kWh, density 820 kg/m³	49.162 L/h
Performance engine	Injector-based	4 injectors, 550 cc/min, 80%, 3 bar	105.600 L/h

Formula Used

Volumetric flow from volume and time:
Q_v = V / t

Mass flow from mass and time:
ṁ = m / t

Mass flow from power and BSFC:
ṁ = P × LF × BSFC / 1000

Injector-based volumetric flow:
Q_inj = n × q × √(P_actual / P_rated) × DC × 0.06

Mass and volumetric conversion:
ṁ = ρ × Q_v and Q_v = ṁ / ρ

Here, Q_v is volumetric flow rate, ṁ is mass flow rate, V is volume, t is time, P is power, LF is load factor, BSFC is brake specific fuel consumption, ρ is density, n is injector count, q is injector rating, and DC is duty cycle.

How to Use This Calculator

Select the calculation mode that matches your known engineering data.
Enter fuel density first, because it drives mass-to-volume conversion.
Fill the fields for your selected method only.
Add fuel price to estimate hourly operating cost.
Add vehicle speed if you want L/100 km output.
Press the calculate button to show results above the form.
Review the result table, projected table, and Plotly chart.
Use the CSV or PDF buttons to export the current calculation.

Frequently Asked Questions

1) What is fuel flow rate?

Fuel flow rate is the amount of fuel consumed over time. It may be expressed as mass flow, such as kg/h, or volumetric flow, such as L/h.

2) Why does density matter in fuel flow calculations?

Density connects mass and volume. Two fuels can have the same liters per hour but different kilograms per hour because their densities differ.

3) When should I use the BSFC method?

Use BSFC when you know engine power, load factor, and brake specific fuel consumption. It is common for engines, gensets, and performance studies.

4) What does injector duty cycle represent?

Duty cycle shows the percentage of time an injector remains open. Higher duty generally increases fuel flow, but excessive duty may reduce tuning margin.

5) Can this calculator estimate road fuel economy?

Yes. If you enter vehicle speed, the tool converts hourly fuel usage into L/100 km, which is useful for moving equipment and vehicles.

6) Why are there several output units?

Engineering teams often compare systems across different standards. Multiple units make it easier to work with process, automotive, marine, and equipment datasets.

7) Does rail pressure affect injector flow?

Yes. Injector flow changes roughly with the square root of pressure ratio. This calculator includes a correction using actual and rated pressure values.

8) What should I export, CSV or PDF?

Use CSV when you need spreadsheet analysis or reporting tables. Use PDF when you want a clean, shareable record of the calculation summary.