Flow Rate Converter Calculator
Convert between all common volumetric flow rate units. From gallons per minute for plumbing to cubic feet per minute for HVAC and barrels per day for petroleum, this converter handles every flow rate unit used in industry.
Understanding Flow Rate Units
Flow rate measures the volume of fluid passing a point per unit of time. The most intuitive unit is liters per second (L/s), which you can visualize as pouring liter bottles every second. For larger flows, cubic meters per hour (m3/h) is common in industrial settings. One cubic meter per hour equals about 4.4 US gallons per minute.
US gallons per minute (GPM) dominates plumbing and water treatment in North America. Fire hydrant flows range from 500 to 1,500 GPM. Swimming pool pumps move 40-80 GPM. Municipal water treatment plants process millions of gallons per day (MGD), where 1 MGD equals about 694 GPM continuously.
Airflow uses cubic feet per minute (CFM) in the US and cubic meters per hour (m3/h) internationally. HVAC engineers size ducts, fans, and filters based on required CFM. A home central air system might need 1,200 CFM total, distributed through ductwork to each room based on its heating and cooling load calculations.
Flow Rate in Plumbing and Water Systems
Residential plumbing design starts with fixture flow rates. A toilet flush uses about 1.6 gallons (6 liters) per flush. A kitchen faucet flows at 2.2 GPM. A washing machine uses 15-30 gallons per load. The main water supply pipe must carry enough flow for peak simultaneous demand without excessive pressure drop through the piping system.
Pipe sizing depends directly on flow rate and acceptable velocity. Water velocity in residential pipes should stay below about 8 feet per second to prevent noise and erosion. A 3/4-inch pipe carries about 10 GPM at this velocity. Knowing the required flow rate in consistent units allows proper pipe diameter selection from standard sizing tables.
Irrigation system design converts between gallons per hour and liters per hour for drip emitters, and GPM for sprinkler heads. A typical drip emitter delivers 1-2 gallons per hour (about 4-8 liters per hour). A pop-up sprinkler head might use 2-5 GPM. Converting between units ensures compatibility when mixing components from different manufacturers.
Flow Rate in Industrial and Petroleum Applications
Chemical processing plants measure flows in cubic meters per hour or liters per minute, with flow meters calibrated for specific fluids. A Coriolis flow meter directly measures mass flow rate, while volumetric flow meters like turbine and vortex types measure volume flow. Converting between mass and volume flow requires knowing the fluid density at operating conditions.
The oil industry uses barrels per day (bbl/d) as its standard production rate unit. One barrel is 42 US gallons or about 159 liters. A refinery processing 200,000 bbl/d handles about 8.4 million US gallons or 31.8 million liters daily. Pipeline capacity is also expressed in barrels per day, and operators must convert between bbl/d and volumetric flow rates for pump sizing.
Natural gas flow rates use standard cubic feet per day (SCFD) or standard cubic meters per day, where gas volume is corrected to standard temperature and pressure conditions. This standardization is necessary because gas volume changes significantly with pressure and temperature. A gas well producing 1 million SCFD might deliver a much smaller actual volume at the high pressures found deep underground.
Frequently Asked Questions
How do I convert GPM to LPM?
Multiply US gallons per minute by 3.785 to get liters per minute. A standard kitchen faucet flows at about 2.2 GPM, which is about 8.3 LPM. Low-flow fixtures reduce this to 1.5 GPM (5.7 LPM) or less to conserve water.
What is CFM used for?
CFM (cubic feet per minute) measures airflow in HVAC systems, ventilation, and pneumatic tools. A typical bathroom exhaust fan moves 50-80 CFM. Central air systems move 400 CFM per ton of cooling. Air compressors are rated by CFM at a specific pressure.
How many barrels per day is a typical oil well?
Production varies enormously. A marginal well might produce 10 barrels per day. An average US well produces about 50-100 bbl/d. Prolific Middle Eastern wells can exceed 10,000 bbl/d. Global oil production is roughly 100 million barrels per day total.
What flow rate do I need for a shower?
Standard showerheads flow at 2.5 GPM (9.5 LPM). Water-saving models use 2.0 GPM (7.6 LPM) or less. The water heater must supply at least this flow rate at the desired temperature. Multiple simultaneous fixtures increase the total flow demand on the system.
How do I convert between volume flow rate and mass flow rate?
Multiply volumetric flow rate by fluid density to get mass flow rate. A flow of 10 liters per minute of water (density 1 kg/L) equals 10 kg per minute. For other fluids, use their specific density. Oil at 0.85 kg/L flowing at 10 LPM has a mass flow rate of 8.5 kg per minute.