Mass Flow Rate Converter

Convert Mass Flow Rate Between Units

Mass Flow Rate Formula

Formula

\[\dot m_{\mathrm{to}}=\dot m_{\mathrm{from}}\frac{f_{\mathrm{from}}}{f_{\mathrm{to}}}\]

Where:

\(\dot m_{\mathrm{from}}\) — numerical mass flow rate entered in the From unit
\(\dot m_{\mathrm{to}}\) — numerical mass flow rate expressed in the To unit
\(f_{\mathrm{from}}\) — kilograms per second represented by one From unit
\(f_{\mathrm{to}}\) — kilograms per second represented by one To unit

The converter first expresses the entered rate in kilograms per second, then divides by the factor for the selected output unit. The physical flow rate stays the same; only its numerical value and unit change.

Mass Flow Rate – Calculation Example

Example: With the default settings, convert a mass flow rate of 1 kilogram per second to kilograms per hour.

\[1\ \mathrm{kg/s}\times\frac{3{,}600\ \mathrm{s}}{1\ \mathrm{h}}=3{,}600\ \mathrm{kg/h}\]

Result: 1 kg/s = 3,600 kg/h.

How to use the calculator

Enter a nonnegative number in Mass flow rate value. For example, enter 1 to reproduce the calculation above.
Choose the current unit from From unit. Select kg/s for the example.
Choose the desired unit from To unit. Select kg/h for the example.
Read Converted Mass Flow Rate. The result includes the selected output unit.

You can select the same unit in both menus to leave the value unchanged. To reverse a conversion, swap the two unit selections and enter the converted value. The menus offer kilograms per second, minute, or hour; grams per second; pounds per second, minute, or hour; and metric tons per hour.

What mass flow rate means

Mass flow rate is the mass that passes a point or cross-section per unit of time. A rate of 1 kg/s means that one kilogram passes that point each second. Unlike a total mass, a flow rate includes a time interval in its unit. It is used to describe streams of liquids, gases, and bulk materials in pipes, ventilation systems, and industrial processes.

Converting units makes rates easier to compare. A short-duration process may be specified in kg/s, while a daily operating report may use kg/h or metric tons per hour. The example result, 3,600 kg/h, does not describe more material flowing than 1 kg/s: there are 3,600 seconds in an hour, so the two numbers describe the same rate.

Mass flow rate differs from mass flux density, which expresses flow per unit area. A flow rate alone cannot tell you how much mass crosses each square meter of an opening; you also need the relevant cross-sectional area. It also differs from molar flow rate, which counts moles per unit of time. Converting between mass and molar flow requires the substance’s molar mass, not just a change of units.

Conversion factors and practical limits

The calculator uses kilograms per second as its intermediate unit. The following factors show the number of kg/s in one unit of each supported rate:

Unit	Equivalent in kg/s
1 kg/s	1
1 g/s	0.001
1 kg/min	1/60
1 kg/h	1/3,600
1 lb/s	0.45359237
1 lb/min	0.45359237/60
1 lb/h	0.45359237/3,600
1 metric ton/h	1,000/3,600

Here, a pound is an avoirdupois pound, and a metric ton is 1,000 kg. “Tons per hour” in this calculator does not mean US short tons or imperial long tons. Check the ton definition in your source data before entering a value.

This is a unit converter, not a flow meter. It does not determine a flow rate from velocity, pipe dimensions, density, or pressure. Those quantities may be needed to establish the original rate, but they do not change a unit conversion once that rate is known. Results are rounded to 10 decimal places, so a very small nonzero rate may appear as zero when expressed in a much larger unit.

Frequently Asked Questions

How do I convert a mass flow rate by hand?

Convert the mass unit and the time unit separately. For example, to change 10 lb/min to kg/h, multiply by 0.45359237 kg/lb and by 60 min/h. The result is about 272.16 kg/h. A useful check is that the numerical value should increase when you change a rate from “per minute” to “per hour” without changing its mass unit.

What is a normal mass flow rate?

There is no universal normal value. An appropriate rate depends on the material, equipment size, and purpose of the process. A small dosing pump and an industrial pipeline can have vastly different rates. Compare your result with the equipment specification or operating target, using the same units and operating conditions. A unit conversion alone cannot tell you whether a flow is safe or sufficient.

How do I convert volumetric flow rate to mass flow rate?

Multiply volumetric flow rate by the material’s density at the relevant conditions: \(\dot m=\rho Q\). For example, a liquid flowing at 2 cubic meters per hour with a density of 1,000 kilograms per cubic meter has a mass flow rate of 2,000 kg/h. For gases, check whether the volume is stated at actual or standard conditions before choosing a density.

How do I find the total mass transferred from a mass flow rate?

Multiply the mass flow rate by the elapsed time if the rate remains constant. At 5 kg/min for 12 minutes, the total is 60 kg. If the rate changes, divide the period into intervals and add the mass transferred in each interval, or integrate the rate over time. Keep the time units consistent with the rate.

Can I enter a mass flow rate in US short tons per hour?

Not directly: the ton option uses metric tons. Convert US short tons per hour to a supported unit first. One US short ton is 2,000 lb, so 1 US short ton/h equals 2,000 lb/h, or 907.18474 kg/h. You can then enter either of those values with its matching unit. Do not select metric tons per hour for an unconverted short-ton value.

Can a mass flow rate be negative?

Yes, a negative rate can indicate flow opposite to a chosen positive direction in a signed engineering calculation. This converter accepts nonnegative inputs, so enter the rate’s magnitude and track direction separately. Zero means no net mass crosses the chosen boundary during the period measured; opposing flows could still be present if the reported figure is a net rate.