Flow Rate Converter

Flow rate is the volume of fluid that passes through a given cross-sectional area per unit of time. It is one of the most fundamental measurements in fluid mechanics, plumbing, engineering, and environmental science. Flow rate describes everything from how quickly water flows through a garden hose to the massive volumes of oil moving through a pipeline or the air delivery rate of a mechanical ventilator in a hospital. Understanding and accurately converting between flow rate units is essential for designing systems, ensuring safety, and complying with international standards.

Flow rate is typically expressed as volume per time. Common metric units include liters per second (L/s), liters per minute (L/min), liters per hour (L/hr), and cubic meters per hour (m³/hr). In the imperial and US customary systems, common units include gallons per minute (GPM), gallons per hour (GPH), cubic feet per minute (CFM), and cubic feet per second (CFS). Each unit is appropriate for different scales and applications: L/s is common in laboratory settings, GPM is the standard for pump specifications in the United States, and CFM is widely used for HVAC airflow measurements.

This converter supports nine flow rate units and allows you to convert between any pair of them instantly. It also displays the input value converted into all supported units simultaneously, giving you a comprehensive view of the flow rate in every relevant system. The swap button lets you quickly reverse the conversion direction without retyping values.

All flow rate conversions work through a common intermediate unit, which in this calculator is liters per second (L/s). The conversion first transforms the input value to L/s, then converts from L/s to the target unit.

Use this calculator to convert between any two flow rate units:

1. Enter the value: Type the numerical value into the input field. You can enter whole numbers, decimals, or scientific notation for very large or small values.
2. Select the source unit: Choose the unit you are converting from using the "From" dropdown. Options include L/s, L/min, L/hr, m³/s, m³/hr, GPM (US), GPH (US), CFM, and CFS.
3. Select the target unit: Choose the unit you want to convert to using the "To" dropdown.
4. Read the result: The main result card shows the converted value. Below it, you can see the input value expressed in all supported units.
5. Swap units: Click the swap button to reverse the conversion direction instantly.

The quick reference section provides common conversion factors for quick mental checks.

The calculator displays your input value converted into all nine supported flow rate units:

• Liters per second (L/s): The metric standard for laboratory and scientific flow measurements. 1 L/s = 60 L/min = 3,600 L/hr.
• Liters per minute (L/min): Commonly used for medical IV drip rates, laboratory flow, and small pump specifications. 1 L/min = 60 L/hr.
• Cubic meters per hour (m³/hr): Used for industrial-scale flow measurements, water treatment plants, and large pump specifications.
• Gallons per minute (GPM, US): The standard unit for pump ratings, water flow in plumbing, and HVAC systems in the United States. 1 GPM ≈ 0.06309 L/s.
• Cubic feet per minute (CFM): Widely used for airflow measurements in HVAC, ventilation, and compressed air systems. 1 CFM ≈ 0.4719 L/s.
• Cubic feet per second (CFS): Used for large-scale water flow in rivers, irrigation, and civil engineering. 1 CFS ≈ 28.317 L/s.

The highlighted row in the all-units table indicates your selected target unit for easy reference.

Flow rate conversion is essential in plumbing and water systems. Residential water pressure is typically measured in GPM in the United States, while international standards often use liters per minute. A standard showerhead delivers about 2.5 GPM (approximately 9.5 L/min), while a kitchen faucet flows at about 1.5 GPM (5.7 L/min). When purchasing fixtures or designing water systems, converting between these units ensures compatibility regardless of the manufacturer's origin.

In HVAC and ventilation engineering, airflow is measured in CFM in the United States and in m³/hr in many other countries. A typical residential HVAC system delivers about 1,000 CFM (approximately 1,699 m³/hr). Proper airflow conversion ensures that equipment specifications match building requirements and that ventilation rates meet local codes and standards.

In industrial and chemical engineering, flow rates must be precisely controlled for processes such as mixing, heating, cooling, and chemical reactions. Pipeline flow rates for oil and gas are often specified in barrels per day, which must be converted to volume-per-time units for pump and valve sizing. In medical settings, ventilator flow rates and IV drip rates use L/min and mL/hr respectively, requiring accurate conversions to ensure patient safety.