How to use this calculator
Enter the pressure, velocity and elevation at point 1, the velocity and elevation at point 2, and the fluid. Add a head loss for real pipe flow with friction.
Formulas
Bernoulli with lossesp1ρg + V1²2g + z1 = p2ρg + V2²2g + z2 + hL
Solved for p₂p2 = p1 + ½ρ(V1² − V2²) + ρg(z1 − z2) − ρghL
Worked example
Water at 200 kPa and 2 m/s, rising 5 m and speeding up to 8 m/s (the default)
- Velocity term: ½ × 998 × (2² − 8²) = −29.9 kPa.
- Elevation term: 998 × 9.807 × (0 − 5) = −48.9 kPa.
- p2 = 200 − 29.9 − 48.9 = 121.1 kPa.
Frequently asked questions
Why does pressure drop when the fluid speeds up?
Energy is conserved along the streamline: kinetic energy gained comes out of pressure energy. That is how venturi meters and carburetors work.
When does Bernoulli not apply?
Across pumps or turbines, in compressible gas flow at high speed, in strongly viscous flow, or between points not connected by the flow.