Free hydraulics and pipe flow calculators
Quick, single-purpose calculators for everyday pipe and duct work: size a line, check a velocity, estimate a pressure drop or a heat loss in a few seconds. Each one runs on the same verified engine as Fluid Network Studio, so the numbers match the full tool. They are free, need no sign-in, and state the method and equations openly so you can check the working.
Use a calculator when you have a single pipe and one question. When you need a whole network - loops, branches, pumps and fans working against a system, heat carried through a plant - build it in the Studio instead, where these same methods solve the network together.
Pipe flow and pressure drop
Head loss and pressure drop from flow, or flow from an available head (Darcy-Weisbach with Colebrook-White).
Pipe heat loss and surface temperature
Total heat loss, temperature drop and the temperature of every insulation layer, including the outer surface for safe-touch checks.
Reynolds number
Laminar, transitional or turbulent.
Darcy friction factor
From Reynolds number and relative roughness (Colebrook-White).
Pipe velocity
Mean velocity from flow and diameter, or the reverse.
Pump power
Hydraulic, shaft and electrical power for a duty.
Hazen-Williams pressure drop
The empirical head-loss method for water.
Ready for a full network? Open the Studio to connect pipes, pumps, fans and boundary conditions and solve the whole system at once, with liquids, gases and heat transfer.
Frequently asked questions
Are these calculators free?
Yes. Every calculator on this page is free and needs no account. Saving and sharing full networks is what the paid Studio plans add.
How accurate are they?
They call the same solver methods as Fluid Network Studio, and each page shows a worked example you can reproduce. Results are only as good as the inputs, so check roughness, diameters and fluid properties.
What units can I use?
Enter values in common engineering units (mm, m, L/s, kPa, degrees C). Everything is computed internally in SI.