Metric datasheets and many international product notes list flow in liters per minute (L/min or lpm), while U.S. fire-flow and sprinkler sheets usually use gallons per minute (gpm). Using the U.S. liquid gallon, 1 gpm = 3.785412 L/min, so L/min ÷ 3.785412 = gpm (and gpm × 3.785412 = L/min). This page is a free browser converter focused on the L/min → gpm direction. It is for learning and quick checks—not a substitute for the criteria adopted by your authority having jurisdiction, manufacturer data, a sealed hydraulic calculation, or review by a licensed design professional. It is not a design stamp and not a PE seal.
How the conversion is used
- Confirm the source uses L/min (or L/s × 60) before you convert.
- Convert with the U.S. liquid gallon factor: Qgpm = QL/min / 3.785412.
- Keep the same flow meaning (rated pump flow, test flow, or demand) when you switch units.
- After units match, continue with friction loss, hydrant, tank duration, or pump sketches in consistent units.
Free calculator
Educational approximation only. Uses 1 gpm = 3.785412 L/min (U.S. liquid gallons). Nothing you enter leaves your browser. For the reverse direction see GPM to LPM. For CFS conversions see GPM to CFS and CFS to GPM. Multi-segment paths live in the Sprinkler Pipe Friction Loss workbook.
Worked example
A datasheet lists 946.353 L/min: 946.353 ÷ 3.785412 ≈ 250 gpm. Conversely, 250 gpm × 3.785412 ≈ 946.4 L/min. Always confirm whether the source used U.S. liquid gallons (this page) versus another gallon definition, and check the result against the adopted edition, manufacturer data, and AHJ—not this page alone.
Next steps: convert the other way with the free GPM to LPM calculator, convert to CFS with the free GPM to CFS calculator, size segment losses with the friction loss calculator or Hazen-Williams friction loss calculator, and build multi-segment paths in the Sprinkler Pipe Friction Loss workbook ($29). Pump and tank tables live in the Fire Pump & Tank Sizing workbook ($49).