Mass Flow Rate & Fluid Dynamics Calculator

Fluid Mechanics, Propulsion & Mass Flow Rate Metrology

Mass Flow Rate is the mass of substance passing through a cross-section per unit time:

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• Universal Mass Flow Conversion Formulas (ASME Standards)**:

m_lb/h (PPH) = m_kg/s × 7,936.641

m_t/h = m_kg/s × 3.60 = m_kg/h1,000

m_kg/s = m_lb/h7,936.641 = m_lb/s × 0.453592

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• Volumetric Flow Equivalence & Continuity Equation**:

V = mρ

Flow Velocity (v) = mρ × A_pipe

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• Standard Propulsion & Chemical Benchmarks**:

• Diesel Fuel Injector: 5.0 g/s 18.0 kg/h 39.68 PPH

• Industrial Steam Boiler: 50.0 kg/s 180.0 t/h 396,832 PPH

• Rocket Engine (LOX Turbopump): 250.0 kg/s 900.0 t/h 1,984,160 PPH

• Commercial Jet Turbofan Airflow: 500.0 kg/s 1,800.0 t/h 3,968,321 PPH

How to Use This Calculator

Enter your Mass Flow Rate Magnitude (ṁ) (e.g. 50 in ṁ), From Mass Flow Rate Unit — choose from Kilograms per Second (kg/s - SI Base Unit), Pounds per Hour (lb/h = PPH - Aviation / Boilers), Kilograms per Hour (kg/h), To Mass Flow Rate Unit — choose from Pounds per Hour (lb/h), Kilograms per Second (kg/s), Metric Tonnes per Hour (t/h), Fluid Density (ρ in kg/m³) (e.g. 1000 in kg/m³), Pipe Inside Diameter (ID in inches) (e.g. 4.0 in inches), and Industrial & Aerospace Benchmark — choose from Custom Mass Flow System, Industrial Boiler Feedwater (50.0 kg/s in 4.0" pipe, ρ=1000) → 396,832 PPH | 180.0 t/h | 792.5 GPM | v = 6.16 m/s, Commercial Jet Turbofan Airflow (500 kg/s, ρ=1.20) → 3,968,321 PPH | 1,800 t/h | 416.7 m³/s air ingestion. Results update instantly as you type — adjust any value to compare scenarios.

The Formula

Volumetric Flow: V_dot = m_dot / rho (in m^3/s -> m^3/h and GPM)

Pipe Flow Velocity: v = V_dot / A_pipe

Worked Example

A boiler plant engineer measuring 50.0 kg/s of feedwater flow converts this to 396,832 PPH, calculating that water at density 1,000 kg/m³ flows at 792.5 GPM and travels at 6.16 m/s inside a 4-inch pipe.

Understanding Your Result

Unit conversions are exact by definition within a given measurement system (e.g., 1 km = exactly 1,000 m). Cross-system conversions (metric to imperial) use defined exchange factors: 1 inch = exactly 2.54 cm; 1 pound = 0.45359237 kg. Round your converted result to match the precision of your original measurement — expressing more decimal places than your input justifies implies false accuracy. For regulatory, legal, or safety-critical applications, verify which measurement system is required by the applicable standard.