Flow - Mass Converter
Convert mass flow rate between kilograms, grams, pounds and tons per second, minute, hour or day. Pick a source and a target unit, enter a value and read the result instantly.
Select two units to see the conversion factor.
Mass flow is mass per time. It is not the same as volumetric flow: converting between them needs the fluid density, which this tool does not assume. For liters or gallons per time use the Flow Converter.
Mass Flow Formula
Every mass flow unit is a mass unit divided by a time unit, so each one is a fixed multiple of one reference unit, the kilogram per second (kg/s). To convert, multiply the value by the size of the source unit in kg/s, then divide by the size of the target unit in kg/s. The pound is defined as exactly 0.45359237 kg, the metric ton as 1,000 kg and the short ton as 907.18474 kg; the time bases are 60 s, 3,600 s and 86,400 s.
What Is Mass Flow Rate?
Mass flow rate is the mass of material that passes a point in a unit of time. It is usually written with the symbol ṁ and its SI unit is the kilogram per second (kg/s). Mass flow is the natural measure whenever the amount of material matters more than the space it occupies: fuel burned by a boiler, steam produced by a plant, coal on a conveyor belt, powder fed into a mixer or a chemical dosed into a process stream.
Mass flow differs from volumetric flow. Volumetric flow counts how much space the fluid fills per unit of time, while mass flow counts how much matter it contains. The two are linked by the density ρ of the fluid, ṁ = ρ × Q, so a given liters-per-minute figure represents very different mass flows for water, oil and a gas. Because density changes with temperature and pressure, mass flow is often preferred for gases and for precise process control.
Engineers use many scales. Kilograms per hour and pounds per hour are common for boilers and process plants, tons per hour for bulk materials and mining, grams per minute for dosing and small feeders, and kilograms per second for physics and fluid-dynamics calculations.
Supported Units
This converter supports the following 31 mass flow units. The last column shows how many kilograms per second one unit equals. The metric ton (tonne, 1,000 kg) and the short ton (US ton, 2,000 lb) are different units, so make sure you pick the one your source uses.
| Unit | Symbol | Value in kg/s |
|---|---|---|
| Kilogram per second | kg/s | 1 |
| Gram per second | g/s | 0.001 |
| Gram per minute | g/min | 1.666666667e-5 |
| Gram per hour | g/h | 2.777777778e-7 |
| Gram per day | g/d | 1.157407407e-8 |
| Milligram per minute | mg/min | 1.666666667e-8 |
| Milligram per hour | mg/h | 2.777777778e-10 |
| Milligram per day | mg/d | 1.157407407e-11 |
| Kilogram per minute | kg/min | 0.01666666667 |
| Kilogram per hour | kg/h | 0.0002777777778 |
| Kilogram per day | kg/d | 1.157407407e-5 |
| Exagram per second | Eg/s | 1e+15 |
| Petagram per second | Pg/s | 1e+12 |
| Teragram per second | Tg/s | 1,000,000,000 |
| Gigagram per second | Gg/s | 1,000,000 |
| Megagram per second | Mg/s | 1,000 |
| Hectogram per second | hg/s | 0.1 |
| Dekagram per second | dag/s | 0.01 |
| Decigram per second | dg/s | 0.0001 |
| Centigram per second | cg/s | 1e-5 |
| Milligram per second | mg/s | 1e-6 |
| Microgram per second | µg/s | 1e-9 |
| Ton (metric) per second | t/s | 1,000 |
| Ton (metric) per minute | t/min | 16.66666667 |
| Ton (metric) per hour | t/h | 0.2777777778 |
| Ton (metric) per day | t/d | 0.01157407407 |
| Ton (short) per hour | ton (US)/h | 0.2519957611 |
| Pound per second | lb/s | 0.45359237 |
| Pound per minute | lb/min | 0.007559872833 |
| Pound per hour | lb/h | 0.0001259978806 |
| Pound per day | lb/d | 5.24991169e-6 |
How to Use the Flow - Mass Converter
- Type the mass flow rate in the value box. Decimals and scientific notation such as 0.0025 or 2.5e-3 are accepted.
- Choose the From unit and the To unit.
- The result appears instantly, or press Convert Now. Very large or very small results are shown in scientific notation.
- Use Swap Units to reverse the conversion, Copy Result to copy the answer, open Show this value in all units for a full list, and Clear to start again.
Step-by-step by hand
- Find the size of each unit in the common base unit (kg/s): 1 kg/h = 0.0002777777778 kg/s and 1 lb/h = 0.0001259978806 kg/s.
- Divide the source size by the target size to get the conversion factor: 0.0002777777778 ÷ 0.0001259978806 = 2.204622622, so 1 kg/h = 2.204622622 lb/h.
- Multiply by your value: 500 kg/h × 2.204622622 = 1,102.311311 lb/h.
Mass flow cannot be negative, so only zero and positive numbers are accepted.
Common Mass Flow Conversions
- Boiler steam output: 10,000 lb/h equals 4,535.9237 kg/h or 1.259978806 kg/s.
- Bulk handling: a conveyor carrying 2 metric tons per hour moves 0.5555555556 kg/s, which is 4,409.245244 lb/h.
- Short tons: 10 short tons per hour is 9,071.8474 kg/h or 9.0718474 metric tons per hour.
- Chemical dosing: 250 g/min equals 15 kg/h.
- Small feeders: 40 mg/min equals 2.4 g/h.
- Emissions reporting: 3.5 metric tons per day equals 145.8333333 kg/h.
Kilogram per Hour Conversion – Common Values
Quick reference for frequently used values
| Kilogram/hour | Pound/hour | Gram/minute | Kilogram/second | Metric ton/day |
|---|---|---|---|---|
| 0.1 | 0.2204622622 | 1.666666667 | 2.777777778e-5 | 0.0024 |
| 1 | 2.204622622 | 16.66666667 | 0.0002777777778 | 0.024 |
| 5 | 11.02311311 | 83.33333333 | 0.001388888889 | 0.12 |
| 10 | 22.04622622 | 166.6666667 | 0.002777777778 | 0.24 |
| 25 | 55.11556555 | 416.6666667 | 0.006944444444 | 0.6 |
| 50 | 110.2311311 | 833.3333333 | 0.01388888889 | 1.2 |
| 100 | 220.4622622 | 1,666.666667 | 0.02777777778 | 2.4 |
| 500 | 1,102.311311 | 8,333.333333 | 0.1388888889 | 12 |
| 1,000 | 2,204.622622 | 16,666.66667 | 0.2777777778 | 24 |
| 5,000 | 11,023.11311 | 83,333.33333 | 1.388888889 | 120 |
Where and Why This Conversion Is Used
- Power and process plants: boiler, steam and fuel flows are quoted in kg/h in most countries and in lb/h in the United States.
- Mining, cement and bulk materials: throughput of conveyors, crushers and feeders is stated in tons per hour.
- Food, pharmaceutical and chemical plants: feeders and dosing pumps are set in grams or kilograms per minute or hour.
- Environmental reporting: emission and discharge rates are given in kg/h, t/day or lb/day depending on the regulator.
- HVAC and refrigeration: refrigerant and steam mass flows are commonly written in kg/s or lb/h.
- Engineering education: kg/s is the base unit in mass-balance and fluid-mechanics problems.
To relate mass flow to volume flow multiply by density yourself, for example 10 m³/h of a liquid with a density of 850 kg/m³ is 8,500 kg/h. Use the Flow Converter for the volume side and the Flow - Molar Converter for moles per time.