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Calcimator

Pipe Flow Rate Calculator

Calculate water flow rate, velocity, and friction loss based on pipe diameter, pressure, length, and material.

Inputs

in
PSI
ft

Results

Flow Rate

1.05 GPM

Velocity0.76 ft/s
Friction Loss40 PSI/100ft
Total Head Loss92.4 ft
Flow Rate (metric)3.98 L/min
How to Use This Calculator
  1. Enter Pipe Diameter (inches) and Supply Pressure (psi).
  2. Set Pipe Length (ft) to account for friction losses.
  3. Select Pipe Material (Copper, PVC/CPVC, Galvanized Steel, or PEX) for the Hazen-Williams coefficient.
  4. Review Flow Rate (GPM) at the specified pressure and length.
  5. Use flow rate to size fixtures, irrigation zones, or booster pumps.

How the result changes with Pipe Diameter

Pipe DiameterFlow Rate
1.435.74 GPM
4.36107.66 GPM
7.89512.27 GPM
111,227.59 GPM

What each input means

Pipe Diameter
Interior diameter of the pipe in inches.
Pressure
Available water pressure at the supply point.
Pipe Length
Total length of the pipe run in feet.
Pipe Material
Pipe material affects friction coefficient and flow capacity.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Pipe Diameter = 0.75, Pressure = 40, Pipe Length = 100, Pipe Material = 1 = 4 input(s) provided
  2. Calculate Flow Rate
    1.05 = 1.05
  3. Calculate Velocity
    Velocity
    0.76 = 0.76
  4. Calculate Friction Loss
    40 = 40

Engine last updated . Checked against 2 independently-derived tests — how we verify calculators.

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