Unit converter · calculator
GPM to LPM & LPM to GPM Flow Rate Converter
Convert flow rate between US gallons per minute and liters per minute.
Method record
What this calculator measures
GPM and LPM describe the same volumetric flow in different unit systems. Unlike PSI-to-GPM, this is a direct unit conversion.
L/min = US GPM × 3.785411784 Use it correctly
Calculation steps
- Confirm that the source uses US gallons.
- Enter GPM.
- Read L/min and m³/h equivalents.
Applicability
Use the model within its limits
Label US and Imperial gallons explicitly because their volumes differ.
What this result represents
- System
- Unit converter
- Formula
- L/min = US GPM × 3.785411784
- Review
- Verify safety-sensitive work with qualified guidance.
Worked Field Example
Worked Example: Industrial Chiller Flow Rate Conversion
Field Scenario: Converting an imported European chiller circulation pump flow rate of 180 LPM to US GPM and m³/h for project engineering documents.
Given Input Parameters
Step-by-Step Mathematical Solution
- US GPM = 180.0 / 3.785411784 ≈ 47.55 US GPM.
- Cubic meters per hour (m³/h) = 180 × 60 / 1000 = 10.80 m³/h.
- Imperial GPM = 180.0 / 4.54609 ≈ 39.59 Imperial GPM.
47.55 US GPM (10.80 m³/h, 39.59 Imperial GPM).
Professional Guidance: Always specify US GPM vs Imperial GPM when working on international or Canadian projects to avoid a 20% sizing error.
Engineering Standard Reference
Volumetric Flow Rate Conversion & Benchmark Lookup Table
Flow rate equivalents across US Customary and Metric volumetric units:
| US GPM | Liters / Minute (LPM) | Liters / Second (L/s) | Cubic Meters / Hour (m³/h) | Common Field Application |
|---|---|---|---|---|
| 1.0 GPM | 3.79 L/min | 0.063 L/s | 0.23 m³/h | Water-saving bathroom sink aerator |
| 2.5 GPM | 9.46 L/min | 0.158 L/s | 0.57 m³/h | Standard showerhead / pressure washer feed |
| 5.0 GPM | 18.93 L/min | 0.315 L/s | 1.14 m³/h | Outdoor hose bibb / small pressure booster |
| 10.0 GPM | 37.85 L/min | 0.631 L/s | 2.27 m³/h | Average 5/8" garden hose / 3-bath house peak |
| 20.0 GPM | 75.71 L/min | 1.262 L/s | 4.54 m³/h | Irrigation zone with 6–8 rotor heads |
| 50.0 GPM | 189.27 L/min | 3.155 L/s | 11.36 m³/h | Light commercial service / fire sprinkler riser |
| 100.0 GPM | 378.54 L/min | 6.309 L/s | 22.71 m³/h | Cooling tower makeup / commercial booster station |
| 500.0 GPM | 1,892.71 L/min | 31.545 L/s | 113.56 m³/h | Single 2.5" fire hydrant discharge @ 20 PSI |
Engineering Note: Exact factors: 1 US GPM = 3.785411784 L/min = 0.227124707 m³/h. 1 m³/h = 4.40286754 US GPM.
Engineering FAQs
Frequently Asked Questions
How does a US gallon differ from an Imperial gallon?
1 US gallon equals 231 cubic inches (3.78541 liters), whereas 1 Imperial (UK) gallon equals 277.42 cubic inches (4.54609 liters). An Imperial gallon is approximately 20.1% larger than a US gallon.
How do you convert GPM to cubic meters per hour (m³/h)?
Multiply US GPM by 0.227125. For example, 100 US GPM = 22.71 m³/h. To convert LPM to m³/h, divide LPM by 16.6667 (or multiply by 0.06).
Why is mass flow (lb/hr or kg/s) sometimes used instead of volumetric flow (GPM / LPM)?
Volumetric flow changes with fluid temperature and density (thermal expansion), whereas mass flow remains constant throughout a closed thermal piping loop.