Example: 25 L/min to US GPM
25 ÷ 3.785411784 = 6.604301...
Result: 6.6043 US GPM
Flow-rate converter
Choose US or Imperial gallons before calculating. Both systems use different gallon volumes.
Enter a flow rate to calculate.
L/s—
L/h—
mL/min—
m³/h—
ft³/min—
US gal/h—
Imperial gal/h—
US barrels/day—
Acre-feet/day—
Practical flow tools
Use the converted flow in common volume, filling, pump, and distribution calculations.
Enter a flow rate and time.
Use a lower percentage for leaks, cycling, or operational losses.
Enter tank and flow details.
Enter target volume and available time.
Enter pump and outlet details.
Compare multiple flow rates
Add values, convert them to a common basis, and review totals, averages, and percentage change.
Add at least one valid flow rate.
Conversion table generator
Create a custom range table for US and Imperial gallons per minute.
| Source value | L/min | US GPM | Imperial GPM | m³/h |
|---|---|---|---|---|
| Generate a table to display values. | ||||
Conversion history
Saved entries remain in this browser until you clear them.
No saved calculations yet.
Formula used
US GPM = L/min ÷ 3.785411784
Imperial GPM = L/min ÷ 4.54609
L/min = US GPM × 3.785411784
L/min = Imperial GPM × 4.54609
One US liquid gallon contains exactly 3.785411784 liters. One Imperial gallon contains exactly 4.54609 liters. The selected gallon standard therefore changes the result. The calculator preserves an unrounded internal value and applies display rounding afterward.
Example: 25 L/min to Imperial GPM
25 ÷ 4.54609 = 5.499231...
Result: 5.4992 Imperial GPM
Example: 10 US GPM to L/min
10 × 3.785411784 = 37.85411784
Result: 37.8541 L/min
Engineering systems may report rated flow under specific pressure, temperature, head, or viscosity
conditions. Unit conversion does not correct for those operating conditions.
How to use this calculator
- Enter the flow rate using a decimal, whole number, or scientific notation.
- Select whether you are converting from L/min or from GPM.
- Choose US liquid gallons or Imperial gallons.
- Set decimal places, significant figures, rounding, and display preferences.
- Review the instant result or submit the form for a server-calculated result.
- Use the practical tools to calculate volume, fill time, required flow, or pump totals.
- Save useful calculations to local history or export a conversion table.
Understanding liters per minute
Liters per minute, written L/min, measures volumetric flow. It tells you how many liters pass a point during one minute. The unit appears in plumbing, pumping, water treatment, irrigation, manufacturing, cooling, laboratory systems, and medical equipment. A reading of 25 L/min means the system moves twenty-five liters every minute when operating under the stated conditions.
Understanding gallons per minute
Gallons per minute, written GPM, also measures volumetric flow. However, “gallon” is not a single universal size. The US liquid gallon is smaller than the Imperial gallon. Therefore, a fixed flow expressed in liters per minute produces a larger numerical value in US GPM than in Imperial GPM. Always include the gallon standard when recording, comparing, purchasing, or specifying equipment.
Choosing appropriate precision
Everyday estimates often need two decimal places. Equipment selection may use one or two decimal places when manufacturer tolerances are broader. Laboratory and engineering work can require more digits, but extra digits do not create extra measurement accuracy. Match the displayed precision to the quality of the source measurement. Significant figures are useful when a measured value has a known number of meaningful digits.
Using the practical tools
The volume tool multiplies flow by time. The tank tool divides volume by effective flow. The required-flow tool divides a target volume by the available time. The pump tool estimates combined parallel flow, required pump count, and equal outlet distribution. Real pump systems can behave differently because total dynamic head, pipe friction, valves, elevation, and pump curves affect delivered flow. Treat simplified pump totals as planning estimates.
Comparing systems responsibly
Confirm that all compared values refer to the same operating conditions. A pump rated at one head pressure may not deliver that flow at another head. Temperature and viscosity can matter for fluids other than water. Pipe diameter, fitting losses, filter loading, and valve position also influence actual flow. Unit conversion translates the number but does not model the entire hydraulic system.
Common applications
Household fixtures, showers, garden hoses, aquarium pumps, irrigation zones, transfer pumps, fire protection equipment, industrial process lines, and water-treatment systems frequently use L/min or GPM. Application presets are useful for quick examples, but they should not replace measured flow or manufacturer data. Use calibrated instruments and approved design procedures for safety-critical work.
Typical application ranges
| Application | Illustrative range | Important note |
|---|---|---|
| Household faucet | Approximately 4–12 L/min | Depends on aerator, pressure, and local efficiency standards. |
| Shower | Approximately 6–15 L/min | Low-flow and older fixtures vary considerably. |
| Garden hose | Approximately 20–60 L/min | Diameter, length, nozzle, and supply pressure affect output. |
| Aquarium pump | Model-specific | Rated flow usually decreases with head height and restrictions. |
| Irrigation zone | Design-specific | Use emitter or sprinkler demand and available pressure. |
| Industrial transfer line | Process-specific | Verify fluid properties, pipe losses, and equipment ratings. |
These ranges are illustrative only. Actual flow should be measured or obtained from authoritative equipment documentation.
Frequently asked questions
How many US GPM is 1 L/min?
One liter per minute equals approximately 0.2641720524 US gallons per minute.
How many Imperial GPM is 1 L/min?
One liter per minute equals approximately 0.2199692483 Imperial gallons per minute.
Why are US and Imperial GPM results different?
The gallon sizes differ. A US liquid gallon contains 3.785411784 liters, while an Imperial gallon contains 4.54609 liters.
Can I convert GPM back to L/min?
Yes. Choose “GPM to L/min,” select the correct gallon standard, and enter the GPM value.
Does pressure change the unit conversion?
No. The numerical unit relationship is fixed. Pressure can change the actual flow delivered by a system, but it does not change how liters and gallons are defined.
Why does the calculator show many decimal places?
More digits can help with intermediate calculations. Select fewer decimal places or significant figures when the source measurement is less precise.
Is local history sent to a server?
No. The history feature uses browser local storage. Clearing browser data or pressing the clear button removes saved entries.
Can I use this for pump sizing?
The calculator supports preliminary arithmetic. Final pump sizing should use pump curves, system head, friction loss, fluid properties, operating margins, and qualified engineering review.