Bernoulli Equation Calculator
Bernoulli's equation states that is constant along a streamline in steady, incompressible, inviscid flow. This calculator solves for the downstream pressure given conditions at two points.
Frequently asked questions
When is Bernoulli's equation valid?
Along a streamline in flow that is steady, incompressible and inviscid, with no pumps, turbines or significant friction between the two points. Violating any assumption — long pipes, viscous fluids, compressible gases near Mach 0.3+ — requires correction terms.
Why did I get a negative pressure?
A negative absolute P₂ means the assumptions broke down: the required pressure drop exceeds what the fluid can supply. Physically this predicts cavitation (vapour bubble formation) in liquids — a warning, not a usable answer.
Is this the same as the energy equation?
Bernoulli is the mechanical-energy balance per unit volume with losses set to zero. The full energy equation adds a head-loss term h_L and pump/turbine work; engineers often write Bernoulli 'with losses' for real pipe systems.