Flow Rate Unit Converter
Convert a flow rate between 13 engineering units at once: GPM, LPM, L/s, L/h, m³/h, m³/s, ft³/s (CFS), CFM, GPH, GPD, barrels per day, Imperial GPM and MGD. Enter one value and the full table updates. If you only need one pair, the dedicated pages below give the factor, a reference table and worked examples.
Enter a value to convert
Flow rate conversion resultFree download
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Schedule 40 pipe sizes, water flow in GPM and LPM at four design velocities, and recommended velocities by application. One PDF, made to pin above the bench.
How It Works
The Flow Rate Unit Converter uses precise conversion factors to translate a flow rate value from one unit to another. Each unit is first converted to a common base unit (litres per minute), then converted to the target unit. This two-step approach ensures accuracy across all supported unit pairs.
Conversion Method
To convert from unit A to unit B:
Result = Value × (Factor_A / Factor_B)
Where Factor_A and Factor_B are the number of litres per minute equivalent to one unit of A and B respectively.
Common Flow Rate Conversions
| From | To | Factor |
|---|---|---|
| 1 GPM | LPM | 3.78541 |
| 1 GPM | m³/h | 0.227125 |
| 1 LPM | GPM | 0.264172 |
| 1 m³/h | GPM | 4.40287 |
| 1 L/s | GPM | 15.8503 |
| 1 CFM | L/s | 0.471947 |
| 1 barrel/day | LPM | 0.110408 |
FAQ
Here you will find the answers to the frequently asked questions about flow rate unit conversion.
Frequently Asked Questions
Which flow rate unit should I use?
Use the unit your equipment data is in and convert at the end. Pump curves and fixtures in the US are in GPM; SI building services and water supply design use L/s; HVAC airflow is CFM in the US and m³/h or L/s elsewhere; water treatment plants are rated in MGD and oil production in barrels per day. Each of the common pairs has its own page above with a table and worked example.
What is the difference between US GPM and Imperial GPM?
US GPM and Imperial GPM use different gallon definitions. One US gallon equals 3.78541 litres, while one Imperial gallon equals 4.54609 litres. An Imperial gallon is approximately 20% larger than a US gallon, so it is important to know which system is being used when specifying flow rates in gallons per minute.
How do I convert cubic meters per hour to GPM?
To convert cubic meters per hour (m³/h) to US gallons per minute (GPM), multiply the m³/h value by 4.40287. For example, 10 m³/h equals approximately 44.03 GPM. This conversion is commonly needed when working with international equipment specifications.
What flow rate units are used in HVAC?
In HVAC engineering, cubic feet per minute (CFM) is the standard airflow unit in the United States. Internationally, cubic meters per hour (m³/h) and litres per second (L/s) are more common. For hydronic (water-based) HVAC systems, GPM is typical in the US, while L/s or m³/h are used in metric countries.
What is a standard flow rate unit for oil and gas?
The oil and gas industry commonly uses barrels per day (bpd) to measure production rates. One US petroleum barrel equals 42 US gallons or approximately 158.987 litres. Daily production rates are reported in bpd, while instantaneous flow measurements may use GPM, m³/h, or other volumetric units depending on the region and application.
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