What is the GPM to LPM Converter?
This tool converts a flow rate measured in US gallons per minute (GPM) into liters per minute (LPM). Flow rate describes the volume of fluid passing a point per unit of time, and it is used in plumbing, irrigation, pumps, HVAC and industrial process design. Because the United States uses gallons while most of the world uses liters, converting between the two is a frequent task for engineers, contractors and DIYers.
How to use it
Enter your flow rate in gallons per minute and the calculator instantly returns the equivalent in liters per minute. It also displays the rate expressed as liters per hour and cubic meters per hour, which are handy for sizing tanks, pumps and pipes.
The formula explained
The conversion relies on the exact relationship between a US liquid gallon and a liter: 1 US gallon = 3.785411784 liters. Since time (minutes) is the same on both sides, you simply multiply the gallon figure by this factor:
$$\text{LPM} = \text{GPM} \times 3.785411784$$
To get liters per hour, multiply LPM by 60. To convert to cubic meters per hour, divide liters per hour by 1000.
Worked example
Suppose a pump delivers 10 GPM. Multiply: $$10 \times 3.785411784 = 37.85 \text{ LPM}.$$ Over an hour that is \(37.85 \times 60 = 2{,}271.25\) LPH, or about 2.271 cubic meters per hour.
FAQ
Is this US or Imperial gallons? This converter uses the US liquid gallon (3.785411784 L). Imperial (UK) gallons are larger at about 4.546 liters.
How do I convert LPM back to GPM? Divide the LPM value by 3.785411784.
What is m³/h used for? Cubic meters per hour is a common unit for larger pumps, water treatment and industrial flow specifications.
