💧 Liters Per Minute Calculator
Calculate LPM flow rate for fluid systems
How to Use This Calculator
Select Calculation Type
Choose "From Volume and Time" to calculate LPM from known volume flow, or "From Pipe Diameter and Velocity" to calculate from pipe specifications.
Enter Values
For volume/time: Enter volume and time with appropriate units. For diameter/velocity: Enter pipe diameter and fluid velocity with appropriate units.
Calculate and Review
Click "Calculate LPM" to see flow rate in liters per minute, gallons per minute, and cubic meters per minute.
Formula
From Volume/Time: LPM = Volume (liters) / Time (minutes)
From Diameter/Velocity: LPM = Area × Velocity × 60,000
Where: Area = π × (Diameter/2)²
Example: 100 liters in 10 minutes
Step 1: LPM = 100 / 10 = 10 LPM
Step 2: GPM = 10 × 0.264172 = 2.64 GPM
Example: 100mm pipe, 1.5 m/s velocity
Step 1: Radius = 100mm / 2 = 50mm = 0.05m
Step 2: Area = π × 0.05² = 0.00785 sq m
Step 3: Flow = 0.00785 × 1.5 = 0.01178 cu m/s
Step 4: LPM = 0.01178 × 60,000 = 706 LPM
About Liters Per Minute Calculator
The Liters Per Minute (LPM) Calculator is an essential tool for engineers, plumbers, water system professionals, and technicians who need to calculate flow rates in metric units. This calculator eliminates guesswork by providing precise LPM calculations from volume/time or pipe diameter/velocity, helping you size pumps, pipes, and fluid systems accurately.
When to Use This Calculator
- Pump Sizing: Calculate LPM requirements for pump selection
- Pipe Sizing: Determine flow rate for pipe design
- Fluid System Design: Calculate flow rates for water, oil, gas, and other fluid systems
- Flow Measurement: Convert measured volumes to LPM flow rates
- System Performance: Verify actual flow rates against design requirements
Why Use Our Calculator?
- ✅ Accurate Calculations: Precise LPM calculations using standard fluid dynamics formulas
- ✅ Multiple Methods: Calculate from volume/time or pipe diameter/velocity
- ✅ Multiple Units: Supports various volume, time, diameter, and velocity units
- ✅ Flow Conversions: Shows LPM, gallons per minute, and cubic meters per minute
- ✅ Time Savings: Instant calculations eliminate manual math
Understanding LPM
LPM Definition: LPM (Liters Per Minute) is a metric unit of flow rate measuring the volume of fluid flowing per minute. It's commonly used internationally for sizing pumps, pipes, and fluid systems, especially in countries using the metric system.
Common LPM Values: Typical household fixtures: faucets (4-11 LPM), showers (8-19 LPM), toilets (6-11 LPM). Industrial systems: pumps (20-200 LPM), large pipes (100-1000+ LPM). The calculator helps determine appropriate flow rates for your system.
Tips for Best Results
- Use Accurate Measurements: Measure volumes and times accurately for precise LPM calculations
- Account for Pressure: Flow rates vary with pressure—measure at operating pressure
- Consider Friction: Actual LPM may be lower due to pipe friction and fittings
- Verify Pipe Diameter: Use inner diameter (ID) for accurate flow calculations
- Check Velocity Limits: Recommended velocity is 1-3 m/s for water systems
Frequently Asked Questions
What is LPM?
LPM stands for Liters Per Minute, which measures flow rate—the volume of fluid flowing per minute. It's the metric equivalent of GPM (Gallons Per Minute) and is commonly used internationally.
How do I calculate LPM from volume and time?
LPM = Volume (liters) / Time (minutes). For example, if 100 liters flows in 10 minutes: LPM = 100 / 10 = 10 LPM. The calculator performs this automatically.
How do I convert LPM to GPM?
1 LPM = 0.264172 GPM. To convert, multiply LPM by 0.264172. For example, 10 LPM = 2.64 GPM. The calculator automatically shows GPM conversion.
How do I calculate LPM from pipe diameter and velocity?
LPM = Area × Velocity × 60,000, where Area = π × (Diameter/2)². For example, a 100mm pipe at 1.5 m/s: Area = 0.00785 sq m, Flow = 0.01178 cu m/s, LPM = 706. The calculator performs this automatically.