Mass flow rate (ṁ) is the mass of fluid passing through a cross-section per unit time, measured in units like kg/s or lb/h. It is fundamental to engineering because it is conserved in steady-state systems (continuity equation), unlike volumetric flow which changes with temperature and pressure. Mass flow is essential for chemical reaction stoichiometry, combustion calculations, process control, and energy balance in thermodynamic systems.
Metric Mass Flow
Convert between metric mass flow units like kg/s, kg/h, g/s, ton/h and more.
Conversion Formula
1 kg/s = 3600 kg/h
Common Conversions
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What is Mass Flow Rate?
Mass flow rate is the amount of mass passing through a given cross-section per unit time. It is a fundamental quantity in fluid mechanics, chemical engineering, and process design. Unlike volumetric flow rate, mass flow rate is independent of temperature and pressure, making it essential for chemical reactions, combustion calculations, and process control.
The SI unit of mass flow rate is kilogram per second (kg/s). However, different industries use different units: the petroleum industry uses barrels per day, HVAC engineers use CFM, chemical engineers use kmol/h, and natural gas engineers use MMSCFD. Our converter handles all of these with scientific precision.
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Formulaṁ = ρ × Q (mass flow = density × volumetric flow)
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SI UnitKilogram per second (kg/s)
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Dimension[M][T]⁻¹ (Mass per Time)
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ConservationConserved in steady-state systems (continuity equation)
Industries & Applications
Mass flow measurement is critical across numerous industries. Each industry has its preferred units and measurement standards.
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Chemical EngineeringUses kg/s, kmol/h for reaction stoichiometry and process design
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Petroleum & GasUses MMSCFD, bbl/day, ton/h for production and pipeline flow
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HVAC & RefrigerationUses CFM, lb/h for air handling and refrigerant flow
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Power GenerationUses kg/h, ton/h for steam and fuel flow in turbines
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PharmaceuticalUses g/h, mg/min for precise dosing and API manufacturing
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Food & BeverageUses kg/h, L/h for production line flow rates
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Mining & MineralsUses tph (tons per hour) for ore processing
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AerospaceUses slug/s, lb/s for rocket propellant flow
Why Professionals Choose This Converter
Engineered for precision and designed for speed, our mass flow converter meets the demands of professional engineers and scientists.
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Scientific PrecisionResults accurate to 10 significant digits using NIST-standard factors
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60+ UnitsFrom kg/s to MMSCFD — all major mass flow units in one place
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Instant ResultsReal-time conversion as you type — no buttons to click
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Works OfflineAll calculations run locally in your browser
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Zero TrackingNo cookies, no analytics, no data collection
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Universal CompatibilityFrom keypad phones to 4K displays — works on every device
Frequently Asked Questions
The SI unit is kilogram per second (kg/s). Other SI-derived units include kg/h, g/s, g/min, and metric ton per hour (t/h). The SI system defines mass flow as a derived quantity with dimension [M][T]⁻¹.
Multiply by 7936.64. The exact conversion is: lb/h = kg/s × (2.20462 lb/kg) × (3600 s/h) = kg/s × 7936.64. For example, 1 kg/s = 7936.64 lb/h. Our converter handles this automatically with full precision.
Mass flow measures mass per time (kg/s) and is conserved regardless of temperature and pressure. Volumetric flow measures volume per time (m³/s) and changes with fluid density. The relationship is: ṁ = ρ × Q, where ρ is density. For gases, volumetric flow varies significantly with temperature and pressure, making mass flow the preferred measurement for process engineering.
MMSCFD stands for Million Standard Cubic Feet per Day. It is the standard unit for natural gas flow in the petroleum industry. "Standard" conditions are typically 60°F (15.6°C) and 14.696 psia (101.325 kPa). While technically volumetric, MMSCFD is often treated as mass flow because at standard conditions, the gas density is fixed. To convert to mass flow, multiply by the gas density at standard conditions (e.g., methane ≈ 0.0424 lb/ft³ at standard conditions).
Use the formula: mass flow = molar flow × molar mass. For example, to convert 1 kmol/h of water to kg/h: 1 kmol/h × 18.015 kg/kmol = 18.015 kg/h. Our converter includes common molar flow units (mol/s, kmol/h, lbmol/h) for quick reference.
A slug is the unit of mass in the US Customary (British Gravitational) system. 1 slug = 32.174 lbm = 14.5939 kg. It is defined as the mass that accelerates at 1 ft/s² when a force of 1 lbf is applied. Slug per second (slug/s) is used in aerospace engineering, particularly for rocket propellant flow calculations in the US.
Our converter delivers results accurate to 10 significant digits using conversion factors from NIST and the International Bureau of Weights and Measures (BIPM). This precision is suitable for engineering calculations, scientific research, and professional applications. Temperature-dependent units (like MMSCFD) use standard reference conditions.
Yes, the ASLI FORM Mass Flow Converter is 100% free forever. No registration, no usage limits, no subscription fees, no advertisements. We do not collect any personal data. All calculations happen locally in your browser.
Yes. Once the page loads, all calculations happen locally in your browser. There is no server-side processing, no API calls, and no internet dependency. Perfect for field work, laboratories, and remote locations.
Absolutely. Our converter is designed with a mobile-first responsive approach and works perfectly on every device — from basic keypad phones to 4K desktop displays. The interface adapts intelligently with horizontal category chips for easy navigation on small screens.
Mass flow measurement is critical in: Chemical Engineering (reaction stoichiometry), Petroleum & Gas (production and pipeline flow), HVAC (air handling), Power Generation (steam and fuel flow), Pharmaceutical (precise dosing), Food & Beverage (production lines), Mining (ore processing), and Aerospace (rocket propellant).
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