GPM to LPM Converter (and LPM to GPM)
Convert US gallons per minute (GPM) to liters per minute (LPM) and back, with exact factors, presets, and engineering-friendly rounding.
Gallons per Minute ⇄ Liters per Minute
Enter a value in either box to see the step-by-step conversion.
Quick GPM ⇄ LPM reference table
| GPM (US) | LPM | GPM (UK) |
|---|
Values are rounded to 2 decimal places. Use the calculator above for custom values and precision.
How to convert GPM to LPM
GPM (gallons per minute) and LPM (liters per minute) are both volumetric flow rate units. They tell you how much fluid passes a point every minute, just in different volume units.
Exact conversion factors
1 US gallon = 3.785411784 liters
1 Imperial (UK) gallon = 4.54609 liters
1 US GPM = 3.785411784 LPM
1 UK GPM = 4.54609 LPM
Formulas
US gallons per minute to liters per minute
LPM = GPMUS × 3.785411784
Liters per minute to US gallons per minute
GPMUS = LPM ÷ 3.785411784
UK gallons per minute to liters per minute
LPM = GPMUK × 4.54609
Liters per minute to UK gallons per minute
GPMUK = LPM ÷ 4.54609
Worked examples
Example 1 – 10 GPM (US) to LPM
You have a pump rated at 10 GPM (US) and want the flow in LPM.
- Use the formula: LPM = GPM × 3.785411784
- Plug in the value: LPM = 10 × 3.785411784
- Compute: LPM = 37.85411784
- Round to 2 decimals: ≈ 37.85 LPM
Example 2 – 50 LPM to GPM (US)
A specification lists a flow of 50 LPM. What is this in US GPM?
- Use the formula: GPM = LPM ÷ 3.785411784
- Plug in the value: GPM = 50 ÷ 3.785411784
- Compute: GPM ≈ 13.2086
- Round to 2 decimals: ≈ 13.21 GPM
Example 3 – 5 GPM (UK) to LPM
A UK datasheet gives 5 GPM (Imperial). Convert to LPM.
- Use the UK factor: LPM = GPMUK × 4.54609
- Plug in the value: LPM = 5 × 4.54609 = 22.73045
- Rounded: ≈ 22.73 LPM
US vs UK gallons – which one should you use?
Most industrial, HVAC, and plumbing applications in North America use US gallons. Many European and older UK documents may use Imperial gallons, which are larger.
- US gallon: 3.785 L
- Imperial gallon (UK): 4.546 L
If a datasheet just says “GPM” and comes from a US manufacturer, it is almost always US GPM. If it is from the UK or older Commonwealth sources, check whether it explicitly says “Imp. gal” or “UK gal”.
Typical flow rates in GPM and LPM
- Domestic tap / faucet: 1–2 GPM ≈ 4–8 LPM
- Low-flow shower head: 1.5–2.5 GPM ≈ 6–9.5 LPM
- Garden hose: 5–10 GPM ≈ 19–38 LPM
- Small irrigation zone: 10–20 GPM ≈ 38–76 LPM
FAQ: GPM to LPM
How do you convert GPM to LPM?
Multiply the GPM value by 3.785411784 for US gallons. For quick mental math, you can use 3.785 or even 3.8 as an approximation.
How do you convert LPM to GPM?
Divide the LPM value by 3.785411784 (US gallons). For a rough estimate, divide by 3.8.
What is 1 GPM in LPM?
1 GPM (US) ≈ 3.785 LPM.
What is 1 LPM in GPM?
1 LPM ≈ 0.2642 GPM (US).
Does this calculator support both directions?
Yes. You can type in either the GPM or the LPM field and the other value updates instantly. Use the rounding selector to match the precision you need for engineering or plumbing work.