Why use mass flow rate instead of volume flow rate?

Mass flow rate stays constant regardless of temperature or pressure changes—volume doesn't. For gases especially, 1 m³ at high pressure contains much more mass than at low pressure. Chemical reactions, energy calculations, and mass balances all require mass flow for accuracy.

How do I convert volume flow to mass flow?

Mass flow = Volume flow × Density. For water: 1 L/min × 1 kg/L = 1 kg/min. For gases, use the ideal gas law to find density at your conditions: ρ = PM/(RT), where P is pressure, M is molecular weight, R is gas constant, T is temperature.

What is mass flow rate used for in engineering?

Mass flow is essential for: heat transfer calculations (Q = ṁ × cp × ΔT), combustion analysis (air-fuel ratios), chemical reactions (stoichiometry), turbomachinery performance, and process control. It's the basis for mass and energy balances in any system.

How is mass flow rate measured?

Common methods include: Coriolis flowmeters (measure mass directly via vibrating tubes), thermal mass flowmeters (heat transfer to flowing gas), and combining volumetric meters with density measurement or calculation. Coriolis meters are most accurate but more expensive.

质量流率 Converter

About Mass Flow Rate Conversion

Mass flow rate measures the mass of material passing a point per unit time—a fundamental quantity in process engineering that remains constant regardless of temperature or pressure conditions. While volume flow rate changes when gases expand or compress, mass flow rate stays the same, making it the preferred measurement for gases, chemical reactions, energy calculations, and any process requiring accurate material accounting.

The SI unit is kilograms per second (kg/s), though practical applications often use kg/h, lb/h, or tonnes/h depending on scale and regional conventions. Mass flow rate is essential in chemical engineering (reactor design, material balances), combustion analysis (air-fuel ratios), steam systems (boiler capacity, turbine performance), HVAC (humidity control), and manufacturing (continuous processing). The energy equation Q = ṁ·cp·ΔT directly uses mass flow rate, and conservation of mass (continuity equation) makes mass flow the most fundamental flow quantity for process control.

Our converter handles all standard mass flow rate units for industrial, chemical, and mechanical engineering applications.

Common Mass Flow Rate Conversions

From	To	Multiply By
kg/s	kg/h	3,600
kg/h	kg/s	0.000278
kg/s	lb/s	2.205
lb/s	kg/s	0.4536
kg/h	lb/h	2.205
lb/h	kg/h	0.4536
kg/s	tonne/h	3.6
tonne/h	kg/s	0.2778
lb/min	kg/s	0.00756
kg/s	lb/min	132.3

Mass Flow Rate Unit Reference

Kilogram per second (kg/s) – The SI unit for mass flow rate. Standard for scientific calculations, thermodynamics equations, and energy analysis. Directly compatible with SI power (watts) and heat capacity (J/kg·K) for heat transfer calculations. Large industrial flows can reach hundreds of kg/s; household applications might be fractions of a kg/s.

Kilogram per hour (kg/h) – The common practical metric unit for industrial processes, boilers, HVAC systems, and continuous flow operations. 1 kg/s = 3,600 kg/h exactly. More intuitive for slower processes where kg/s would give fractional values. Steam boiler capacities and fuel consumption are typically specified in kg/h.

Pound per hour (lb/h) – US standard unit for steam systems, HVAC applications, and industrial processes in North America. Dominant in boiler specifications, steam tables, and American process engineering documentation. 1 lb/h ≈ 0.4536 kg/h. Steam flow calculations in the US are virtually always in lb/h.

Tonne per hour (t/h) – Used for large-scale industrial processes, bulk material handling, mining operations, and power plants where flows are substantial. 1 t/h = 1,000 kg/h. Cement plants, steel mills, and large power stations commonly specify flows in tonnes per hour.

Pound per second (lb/s) – Common in aerospace engineering, jet engine specifications, and high-flow rate applications. Jet engine mass flow rates (100-500 lb/s for large turbofans) and rocket engine propellant flows use this unit. 1 lb/s = 3,600 lb/h = 0.4536 kg/s.