Size a pipe for a target flow rate and check the velocity against recommended limits.
Excess velocity causes noise, erosion and steeply rising pressure loss, so pipes are sized to a velocity limit rather than simply to fit the flow. Typical limits are 1 to 3 m/s for water in building services. Pressure loss rises with roughly the square of velocity, so a pipe one size too small costs pumping energy for its entire life.
Pipe Flow
v = Q ÷ A; minimum diameter = √(4Q ÷ (π v_max))
v = Q ÷ A; minimum diameter = √(4Q ÷ (π v_max)) Excess velocity causes noise, erosion and steeply rising pressure loss, so pipes are sized to a velocity limit rather than simply to fit the flow. Typical limits are 1 to 3 m/s for water in building services.
Pressure loss rises with roughly the square of velocity, so a pipe one size too small costs pumping energy for its entire life.
This calculator takes 3 inputs: Required flow rate, Pipe internal diameter, Recommended maximum velocity. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.