Water Flow Rate Calculator – Calculate Flow Rate in Pipes
Determine water or fluid flow rates quickly with our flow rate calculator. Enter pipe diameter and velocity to calculate volumetric flow in liters per second or gallons per minute.
How to Calculate Water Flow Rate
Choose Calculation Method
Select velocity method (pipe diameter + flow speed) or pressure method.
Enter Pipe Parameters
Input pipe diameter and either flow velocity or pressure difference.
Get Flow Rate Results
See flow rate in cubic meters/second, liters/second, and gallons per minute.
Key Features of This Flow Rate Calculator
**Dual Calculation Methods**
Calculate from velocity (Q = A × v) or estimate from pressure using Torricelli's law.
**Multiple Unit Outputs**
Results shown in m³/s, L/s, and GPM for various engineering applications.
**Cross-Sectional Area**
Automatically calculates pipe area from diameter for flow computations.
**Free Engineering Tool**
Useful for plumbing, hydraulics, irrigation, and fluid mechanics calculations.
Frequently Asked Questions
What is flow rate?
Flow rate (Q) is the volume of fluid passing through a pipe per unit time. It's calculated as Q = A × v, where A is cross-sectional area and v is flow velocity.
How do I measure pipe flow rate?
Measure the pipe diameter to calculate area, then measure or estimate flow velocity. Multiply area by velocity to get volumetric flow rate.
What affects water flow rate in pipes?
Pipe diameter, pressure difference, pipe length, roughness, and fluid viscosity all affect flow rate. Larger diameter and higher pressure increase flow.
How do I convert GPM to liters per second?
1 GPM (gallon per minute) = 0.0631 liters per second. Multiply GPM by 0.0631 to convert, or divide L/s by 0.0631 to get GPM.
What is a good flow rate for household plumbing?
Typical household fixtures: faucets 1.5-2.2 GPM, showerheads 1.5-2.5 GPM, toilets 1.28-1.6 GPF. Main supply lines should deliver 8-12 GPM total.
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