Flow Rate Conversion Calculator
Written by Thierno Sadou Diallo, formula verified per our methodology • Last checked on 9/10/2026
To convert a flow rate, it is reduced to a common unit (the liter per second), then converted into the new unit. For example, 1 m³/h equals about 16.67 liters per minute.
Explanation
Volumetric flow rate, the amount of fluid passing per unit of time, is expressed in different units depending on context: the liter per second (L/s) and the liter per minute (L/min) are commonly used for domestic flows (tap, shower, small pump); the cubic meter per hour (m³/h) is the reference for larger flows (water networks, ventilation, industrial pumps); the US gallon per minute (gal/min or GPM) remains the reference unit in the United States, notably for pumps and plumbing equipment. Converting a flow rate means multiplying the value by the factor that reduces it to L/s, then dividing by the target unit's factor — exactly what this calculator does. The gallon used here is the US gallon (3.785411784 L exactly), to be distinguished from the British imperial gallon (about 4.546 L, noticeably larger), a frequent confusion that can throw off a flow calculation by nearly 20% if the wrong definition is used. To calculate a flow rate from the flow velocity and pipe cross-section rather than converting a known unit, see our volumetric flow rate calculator; to size a pipe diameter from a target flow rate, our pipe diameter calculator.
Example: converting 1 m³/h to liters per minute
Inputs
Value: 1. Starting unit: m³/h. Target unit: L/min.
Calculation
1 m³/h = 1,000 L ÷ 60 min ≈ 16.67 L/min.
Result
1 m³/h equals about 16.67 liters per minute.
Frequently asked questions
What is the difference between the US gallon and the imperial gallon?
They are two distinct units despite the same name: the US gallon (used in the United States) equals exactly 3.785411784 liters, while the British imperial gallon equals about 4.54609 liters, nearly 20% more. This calculator uses the US gallon exclusively, the one most commonly used for pump and plumbing flow rates.
Why is m³/h preferred for large flow rates?
Because expressing a large flow rate in liters per second or per minute would give unwieldy numbers with many digits. The cubic meter per hour, a unit a thousand times larger than the liter per hour, is more practical to handle for water network, ventilation, or industrial flows.
Does this calculator also convert mass flow rates (kg/s)?
No, this calculator only covers volumetric flow rates (a volume per unit of time). A mass flow rate (a mass per unit of time) requires also knowing the fluid's density to be converted into a volumetric flow rate, an additional input not handled here.