Kilogram per second (kg/s)
Kilogram per minute (kg/min)
Kilogram per hour (kg/hr)
Gram per second (g/s)
Gram per minute (g/min)
Gram per hour (g/hr)
Pound per second (lb/s)
Pound per minute (lb/min)
Pound per hour (lb/hr)
Metric Ton per hour (t/hr)
Short Ton per hour (US ton/hr)
Kilogram per second (kg/s)
Kilogram per minute (kg/min)
Kilogram per hour (kg/hr)
Gram per second (g/s)
Gram per minute (g/min)
Gram per hour (g/hr)
Pound per second (lb/s)
Pound per minute (lb/min)
Pound per hour (lb/hr)
Metric Ton per hour (t/hr)
Short Ton per hour (US ton/hr)
Converted Result
0
function calculateFlowConversion() {
var valInput = document.getElementById("flowValue").value;
var fromUnit = document.getElementById("fromUnit").value;
var toUnit = document.getElementById("toUnit").value;
var resultBox = document.getElementById("resultBox");
var resultValue = document.getElementById("resultValue");
var conversionDetail = document.getElementById("conversionDetail");
var formulaDisplay = document.getElementById("formulaDisplay");
// Validate Input
if (valInput === "" || isNaN(valInput)) {
alert("Please enter a valid numeric flow value.");
return;
}
var inputValue = parseFloat(valInput);
// Conversion factors relative to Kilogram per Second (kg/s)
// 1 [Unit] = Factor * [kg/s]
var factors = {
"kg_s": 1.0,
"kg_min": 1.0 / 60.0,
"kg_hr": 1.0 / 3600.0,
"g_s": 0.001,
"g_min": 0.001 / 60.0,
"g_hr": 0.001 / 3600.0,
"lb_s": 0.45359237,
"lb_min": 0.45359237 / 60.0,
"lb_hr": 0.45359237 / 3600.0,
"t_hr": 1000.0 / 3600.0, // Metric Ton per hour
"st_hr": 907.18474 / 3600.0 // Short Ton (US) per hour
};
var unitLabels = {
"kg_s": "kg/s",
"kg_min": "kg/min",
"kg_hr": "kg/hr",
"g_s": "g/s",
"g_min": "g/min",
"g_hr": "g/hr",
"lb_s": "lb/s",
"lb_min": "lb/min",
"lb_hr": "lb/hr",
"t_hr": "t/hr",
"st_hr": "US ton/hr"
};
// Calculation:
// 1. Convert Input to Base (kg/s) -> Input * fromFactor
// 2. Convert Base to Target -> Base / toFactor
var fromFactor = factors[fromUnit];
var toFactor = factors[toUnit];
// Base value in kg/s
var baseValue = inputValue * fromFactor;
// Final converted value
var finalResult = baseValue / toFactor;
// Formatting logic: check for very small or very large numbers
var displayResult;
if (Math.abs(finalResult) 999999) {
displayResult = finalResult.toExponential(4);
} else {
// Check if integer
if (Number.isInteger(finalResult)) {
displayResult = finalResult;
} else {
displayResult = finalResult.toFixed(4);
// remove trailing zeros after decimal if desired, but fixed(4) is standard for engineering
displayResult = parseFloat(displayResult);
}
}
resultBox.style.display = "block";
resultValue.innerHTML = displayResult + " " + unitLabels[toUnit] + "";
conversionDetail.innerHTML = inputValue + " " + unitLabels[fromUnit] + " = " + displayResult + " " + unitLabels[toUnit];
// Formula Display
// Formula: Output = Input * (FromFactor / ToFactor)
var conversionRatio = fromFactor / toFactor;
var ratioDisplay = conversionRatio.toExponential(4);
if (conversionRatio >= 0.01 && conversionRatio <= 100) {
ratioDisplay = conversionRatio.toFixed(4);
ratioDisplay = parseFloat(ratioDisplay);
}
formulaDisplay.innerHTML = "Multiplier Factor: " + ratioDisplay + "Logic: " + inputValue + " × " + ratioDisplay;
}
Understanding Mass Flow Rate Conversion
Mass flow rate is a fundamental concept in physics, fluid dynamics, and engineering. It represents the mass of a substance that passes through a given cross-sectional area per unit of time. Unlike volumetric flow rate, which can change based on the density of the fluid (affected by temperature and pressure), mass flow rate remains constant for a continuous system due to the conservation of mass.
This calculator allows engineers, technicians, and students to quickly convert between common Imperial and Metric units used to measure mass flow. Whether you are calculating fuel consumption, analyzing HVAC systems, or designing chemical processes, accurate unit conversion is critical.
Why Mass Flow Rate Matters
In many engineering applications, the mass of the fluid is the variable of interest rather than the volume. For example:
Combustion Engines: The air-to-fuel ratio is calculated based on mass, not volume, to ensure stoichiometric combustion.
Chemical Reactions: Stoichiometry relies on the molar or mass balance of reactants entering a reactor.
Compressible Fluids: Gases change volume significantly with pressure changes, making volumetric flow rate an unreliable metric without temperature/pressure compensation. Mass flow ignores these fluctuations.
Common Units Explained
Depending on the industry and the scale of the operation, different units are utilized:
Process plants, steam generation, large scale manufacturing.
Imperial / US Customary
lb/hr, lb/min
HVAC systems in the US, steam boilers, oil and gas.
The Conversion Math
To convert mass flow rates manually, you generally need to convert the mass unit and the time unit separately.
Step 1: Convert Mass
For example, to convert 10 lb/s to kg/s, you multiply by the mass factor (1 lb ≈ 0.453592 kg). 10 lb/s × 0.453592 = 4.53592 kg/s
Step 2: Convert Time
If you are converting from seconds to hours, you multiply by 3600 (since there are 3600 seconds in an hour). Note that if the time unit is in the denominator (per second vs per hour), the math essentially flips based on whether you are going from a smaller unit to a larger unit.
Mass Flow Rate Formula
If you have the density of the fluid and the volumetric flow rate, you can calculate the mass flow rate using this fundamental equation:
ṁ = ρ × Q
ṁ (m-dot): Mass Flow Rate (e.g., kg/s)
ρ (rho): Density of the fluid (e.g., kg/m³)
Q: Volumetric Flow Rate (e.g., m³/s)
Frequently Asked Questions
What is the difference between lb/hr and kg/hr?
lb/hr (pounds per hour) is an Imperial unit, while kg/hr (kilograms per hour) is a Metric unit. To convert roughly, 1 kg/hr is approximately equal to 2.2046 lb/hr.
Does temperature affect mass flow rate?
In a closed system, mass is conserved, so the mass flow rate is constant regardless of temperature changes. However, temperature changes do affect density and volumetric flow rate. This is why mass flow meters (like Coriolis meters) are often preferred over volumetric meters for high-precision applications.
How do I convert tons per hour?
It depends on the "ton". A Metric Ton is 1,000 kg. A US Short Ton is approximately 907.18 kg. A UK Long Ton is approximately 1,016 kg. Always verify which ton is being referenced in your technical data sheets. This calculator supports Metric Tons (t/hr) and US Short Tons (US ton/hr).