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🌊 Bernoulli Equation Calculator

Enter 5 of the 6 values — pressure (P), velocity (v), and height (h) at two points (1 and 2) — and this calculator instantly solves for the remaining one using Bernoulli's equation.

Enter the fluid density (ρ), pick which of the 6 variables (P1, v1, h1, P2, v2, h2) to solve for below, and fill in the other 5. Assumes incompressible, steady, inviscid flow (SI units).

Point 1
Point 2
Result

Equation: P₁ + ½ρv₁² + ρgh₁ = P₂ + ½ρv₂² + ρgh₂ (g = 9.80665 m/s²)

GUIDE

Learn more

01

What is Bernoulli's Equation?

Bernoulli's equation is a core principle of fluid dynamics stating that for an incompressible, inviscid, steady flow, the sum of pressure energy, kinetic energy, and potential energy is conserved along a streamline.

P + ½ρv² + ρgh = constant

As velocity increases, pressure decreases, and vice versa with height, so the three terms trade off against each other. First proposed by Daniel Bernoulli in 1738, it underlies applications from aircraft lift to pipe flow and venturi meters.
02

The Relation Between Two Points

For two points 1 and 2 along a flow path:

P₁ + ½ρv₁² + ρgh₁ = P₂ + ½ρv₂² + ρgh₂

Given the density (ρ) and 5 of the 6 variables (P1, v1, h1, P2, v2, h2), this calculator algebraically rearranges this equation to solve for the remaining variable. When solving for a velocity, if the resulting v² is negative, the input combination has no physical solution and an error is shown.
03

Assumptions and Limitations

This calculation assumes the fluid is incompressible (constant density), inviscid (no friction losses), and in steady flow (no time variation). Real pipe systems have friction losses, turbulence, and possibly compressibility effects, requiring an extended energy equation with loss terms for precise engineering design.

Frequently asked questions

Why do I need to enter 5 values?
Bernoulli's equation is a single equality linking P1, v1, h1, P2, v2, h2, and density ρ. Knowing 5 of the 6 variables lets you algebraically solve for the remaining one uniquely.
When does "no physical solution" appear?
When solving for a velocity (v1 or v2), rearranging the equation yields a v² value. If the other inputs make this value negative, no real square root exists, meaning the input combination is not physically possible.
Can this be used for compressible fluids (gases)?
This calculator assumes constant-density incompressible flow. It can be a reasonable approximation for low-speed gas flow, but is not suitable for high-speed compressible flow at high Mach numbers.