GPM to LPM Converter

Convert US gallons per minute (GPM) to litres per minute (LPM). One US gallon is defined as exactly 3.78541 litres, so the conversion is a single multiplication. This is the conversion you need when reading a US pump curve against a metric specification.

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GPM to LPM conversion result

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How It Works

GPM is the standard volumetric flow unit on US pump curves, irrigation equipment and plumbing fixtures. LPM is its direct metric counterpart and appears on almost all equipment sold outside the United States. Because both units measure volume per minute, converting between them never requires pipe diameter, pressure or fluid density — only the gallon-to-litre ratio.

GPM to LPM Formula

LPM = GPM × 3.78541

One US gallons per minute equals 3.78541 litres per minute. Going the other way, one litres per minute equals 0.264172 US gallons per minute.

Worked Example

Converting 100 GPM:

100 × 3.78541 = 378.541 LPM

GPM to LPM Conversion Table

GPM LPM
1 GPM 3.78541 LPM
5 GPM 18.9271 LPM
10 GPM 37.8541 LPM
25 GPM 94.6352 LPM
50 GPM 189.27 LPM
100 GPM 378.541 LPM
250 GPM 946.353 LPM
500 GPM 1892.71 LPM
1000 GPM 3785.41 LPM

Going the other way? Use the LPM to GPM converter. For any other unit pair, the full flow rate converter handles all ten supported units.

FAQ

Common questions about converting US gallons per minute to litres per minute.

Frequently Asked Questions

How do I convert GPM to LPM?

Multiply the GPM value by 3.78541. For example, 100 GPM x 3.78541 = 378.541 LPM. The factor is exact, because one US gallon is defined as exactly 3.785411784 litres.

How many litres per minute is 1 GPM?

One US gallon per minute equals 3.78541 litres per minute. A typical household tap running at 2 GPM is therefore delivering about 7.57 LPM.

Is US GPM the same as Imperial GPM?

No. One US gallon is 3.78541 litres, but one Imperial gallon is 4.54609 litres — about 20% larger. If a specification comes from the UK, Canada or another Commonwealth source, check which gallon it means before converting, because using the wrong one introduces a 20% error.

What is 10 GPM in litres per minute?

10 GPM equals 37.8541 LPM. For quick mental estimates, multiplying by 3.8 is accurate to within about 0.4%.

Do I need pipe diameter to convert GPM to LPM?

No. Both GPM and LPM measure volume per unit of time, so the conversion is a pure unit change. Pipe diameter is only needed when converting a flow rate to a velocity, such as feet per second — use the velocity calculator for that.

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