Flow Rate Converter
Convert American pump and HVAC flow rates in seconds with this free tool that switches between gallons per minute, cubic feet per minute, liters per minute, liters per second, milliliters per second, and cubic meters per hour, showing the exact formula, working instantly offline with no signup required ever for contractors.
Convert volumetric flow rates between L/min, m3/h, gpm, and cfs with this free flow rate converter for piping and pumps.
Calculator Inputs
About Flow Rates
Convert American pump and HVAC flow rates in seconds with this free tool that switches between gallons per minute, cubic feet per minute, liters per minute, liters per second, milliliters per second, and cubic meters per hour, showing the exact formula, working instantly offline with no signup required ever for contractors.
How flow rate conversion works in seconds: Enter any value, pick a source unit among GPM, CFM, liters per minute, liters per second, milliliters per second, or cubic meters per hour, then pick a target for an instant result anchored through liters per minute. The browser multiplies by the source factor, divides by the destination factor, and rounds to four decimals at $0 cost with no signup required, making it free and instantly offline for field work.
\nResults format and anchor factors: The headline result shows the converted value with its label, and a formula line records both sides like 2.5 GPM equals 9.4635 liters per minute. Anchors are 3.78541 liters per minute per GPM and 28.3168 per CFM. A Chicago tech balancing an $8,000 rooftop on 09/15/2026 converts 400 CFM per ton into 679.6 cubic meters per hour for the metric submittal.
\nLiquids versus air in United States practice: The math is identical for liquids and gases, but context decides the unit: GPM and liters per minute for plumbing and irrigation, CFM and cubic meters per hour for duct airflow. Federal showerheads cap at 2.5 GPM, faucets at 2.2, and HVAC rules of thumb run 400 CFM per ton. An Austin plumber sizing a $350 valve on 06/12/2026 quotes both GPM and liters per minute for the inspector.
\nPrivacy and local browser execution: This converter runs entirely in your browser with zero server calls, so job addresses, pump schedules, and bid figures never leave your device. Nothing is transmitted, logged, or stored anywhere. Whether you are a Miami irrigator zoning a $2,200 system or a New York super auditing a $4,000 riser, the numbers stay local.
\nPump curves and field workflow: Nameplate maximums mislead because flow collapses as head pressure rises, so always read the pump curve at your actual head before converting. A Denver pool builder matching a $5,500 filter pump on 09/20/2026 converted 10 GPM to 37.85 liters per minute, then checked the curve at twenty feet of head to confirm turnover targets.
\nCommon flow mistakes to avoid: Do not quote volume rate for viscous fluids without checking pump derate, and do not confuse US gallons with imperial gallons in imported specs. Remember that mass rate needs density on top of volume rate. A Seattle aquarist cycling a $900 reef tank learned that ten times hourly turnover means converting tank gallons to GPM before picking the return pump.
Where it is used
Austin plumbers sizing $350 shower valves at 2.5 gallons per minute, Chicago HVAC techs balancing $8,000 rooftops near 400 cubic feet per minute per ton, Miami irrigators zoning $2,200 drip lines by liters per minute, Denver pool builders matching $5,500 filter pumps, Seattle aquarists cycling $900 reef tanks, and New York supers auditing $4,000 riser flows.
How to use the Flow Rates
- Value — enter the value (e.g. 10).
- From — enter the value.
- To — enter the value.
- Calculate — press the Calculate button to see the result instantly above.
Formula
result = value * factor[from] / factor[to] anchored to L/min (GPM 3.78541, CFM 28.3168).
Examples
Showerhead rating
HVAC airflow
Pump specification
Frequently Asked Questions
- What flow does a house need?
- Typical fixtures run 4 to 10 liters per minute each, while whole house supply is usually sized for 20 to 40 liters per minute of peak demand.
- What is the difference between GPM and CFM?
- GPM measures liquids and CFM measures gases, but both are volume per time so they convert directly. Context decides which unit you quote.
- Why do pump curves matter more than maximums?
- Flow collapses as head pressure rises. The curve value at your actual head beats any single maximum flow number.
- Which units does the tool convert?
- Liters per minute, liters per second, milliliters per second, cubic meters per hour, US GPM, and CFM, all anchored to liters per minute.
- Does the converter work offline?
- Yes. All math runs locally in your browser at $0 cost with no signup required.
- Can it handle viscous fluids?
- It converts volume rate only. For syrups and slurries, check the pump derate curve because viscosity cuts real flow.