LPM to GPM

Two units, one flow rate

LPM to GPM converts litres per minute into US gallons per minute. Metric pump, HVAC, irrigation, plumbing, and industrial documents often use LPM, while US equipment data usually uses GPM.

Example: 10 LPM × 0.264172 = 2.642 GPM

Litres per minute

LPM means litres per minute. It measures the volume of liquid or gas that passes through a pipe, valve, pump, or system every minute. It is widely used in metric engineering documents.

Example: A 60 LPM pump moves 60 litres every minute.

Gallons per minute

GPM means gallons per minute. On this page it means US gallons per minute, the common flow-rate unit for pumps, plumbing fixtures, irrigation equipment, pressure washers, and industrial water systems in the United States.

Example: A 2.0 GPM showerhead uses 7.571 LPM.

Unit system and origin

LPM belongs to the metric system and is based on the litre. GPM belongs to the US customary system when US gallons are used. Both describe the same physical quantity: volumetric flow rate.

Where the factor comes from

The factor 0.264172 comes from the exact US liquid gallon value of 3.785411784 litres. Dividing one litre by one US gallon gives the LPM to US GPM multiplier.

Imperial GPM uses a different factor: 0.219969.

Step-by-step calculation

Use GPM = LPM × 0.264172. For a centrifugal pump running at 75 LPM, the calculation is 75 × 0.264172 = 19.813 US GPM.

Formula: GPM = LPM × 0.264172

The exact value

1 LPM equals 0.264172 US GPM. For Imperial gallons, 1 LPM equals 0.219969 Imperial GPM. Always confirm which gallon standard is used before sizing pumps, pipes, or valves.

US and Imperial GPM table

The table uses 0.264172 for US GPM and 0.219969 for Imperial GPM. These factors are different because US and Imperial gallons have different volumes.

The US gallon standard

A US liquid gallon is exactly 3.785411784 litres. Multiplying any LPM value by 0.264172 gives US GPM, which is the standard used by most US pump, plumbing, irrigation, and pressure-washer data.

Formula: US GPM = LPM × 0.264172

The Imperial gallon

An Imperial gallon is exactly 4.54609 litres, about 20 percent larger than a US gallon. To convert LPM to Imperial GPM, multiply by 0.219969.

Formula: Imperial GPM = LPM × 0.219969

Municipal and domestic water systems

Water networks, treatment plants, and building services often mix metric and US equipment data. LPM to GPM conversion keeps pipe sizing, pump ratings, meter calibration, and specification checks in the same unit system.

Example: 30 LPM water flow = 7.925 US GPM

Cross-market pump sizing

European and Asian pump curves often use LPM or m³/h, while US pump curves often use GPM. Converting LPM to GPM helps compare duty points, flow ranges, and system requirements.

Example: 120 LPM pump capacity = 31.7 GPM

Irrigation zone flow

Irrigation controllers, valves, sprinklers, and drip emitters may publish flow in different units. Convert every emitter and zone to one unit before checking pipe capacity or controller limits.

Example: 20 LPM irrigation zone = 5.283 GPM

Fixture and code checks

Plumbing fixture limits in the United States are often written in GPM, while imported taps, showers, and heaters may be rated in LPM. Conversion lets you compare the same flow rate against code and product data.

Example: 8 LPM faucet flow = 2.113 GPM

Cleaning power and flow rate

Pressure washers are compared by pressure and flow. US models often publish GPM, while many metric models publish LPM. Converting LPM to GPM makes cleaning-unit comparisons easier.

Example: 8 LPM pressure washer = 2.113 GPM

Hydraulic pump and motor matching

Hydraulic pumps, motors, valves, and cylinders must be matched by flow. Converting LPM to GPM prevents mismatched components when metric hydraulic equipment is used with US datasheets.

Example: 40 LPM hydraulic pump = 10.567 GPM

Converting US GPM back to LPM

Multiply GPM by 3.785411784 to convert US gallons per minute back to litres per minute. This is useful when US equipment data must be written in metric project documentation.

Example: 5 GPM × 3.785411784 = 18.927 LPM

GPM to LPM reference table

The values below use the US gallon factor of 3.785411784 litres per gallon.

Volumetric flow-rate units

Flow rate measures how much fluid volume passes a point per unit of time. LPM, GPM, CFM, LPS, and m³/h all measure the same physical quantity at different scales. Always identify the gallon or cubic unit standard before engineering use.