EngineeringFluid staticsUniversity
IBUndergraduate

Hydrostatic head Calculator

Converts a fluid head into the equivalent pressure difference.

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Pressure Difference

Formula first

Overview

Hydrostatic head is the height of a fluid column that represents a pressure. For a constant-density fluid, pressure difference is density times gravity times head.

Symbols

Variables

P = Pressure Difference, = Fluid Density, g = Gravitational Acceleration, = Pressure Head

Pressure Difference
Pa
Fluid Density
Gravitational Acceleration
Pressure Head

Apply it well

When To Use

When to use: Use this when a pressure is reported as metres of fluid head or when converting a level difference to pressure.

Why it matters: Head units are common in pumps, tanks, and hydraulic systems because they describe pressure in terms of an equivalent fluid height.

Avoid these traps

Common Mistakes

  • Using the process fluid density when the head is actually a manometer-fluid height.
  • Forgetting that head in metres is not pressure until multiplied by rho g.

One free problem

Practice Problem

What pressure is equivalent to 12 m of water head if density is 1000 kg/ and g is 9.81 m/?

Fluid Density1000 kg/m^3
Gravitational Acceleration9.81 m/s^2
Pressure Head12 m

Solve for: pressure

Hint: Use P = rho g h.

The full worked solution stays in the interactive walkthrough.

References

Sources

  1. Engineering LibreTexts, 7.9: Fluid Statics, accessed 2026-04-09
  2. OpenStax University Physics Volume 1, Pressure in Fluids, accessed 2026-04-09
  3. Munson, Young, Okiishi, Huebsch, and Rothmayer, Fundamentals of Fluid Mechanics, Wiley, 2013
  4. NIST CODATA Value of the Standard Acceleration of Gravity
  5. IUPAC Gold Book
  6. Wikipedia article 'Hydrostatic pressure'
  7. NIST Chemistry WebBook
  8. Britannica