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Manometer for gas Calculator

Calculates gas pressure difference from a manometer-fluid column.

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Pressure Difference

Formula first

Overview

For gas manometers, the gas density is often small compared with the manometer-fluid density. The pressure difference is then well approximated by g h.

Symbols

Variables

- = Pressure Difference, = Manometer Fluid Density, g = Gravitational Acceleration, h = Height Difference

Pressure Difference
Pa
Manometer Fluid Density
Gravitational Acceleration
Height Difference

Apply it well

When To Use

When to use: Use this gas-manometer approximation when the manometer liquid is much denser than the gas being measured.

Why it matters: It provides a simple way to measure low gas pressure differences with a liquid column.

Avoid these traps

Common Mistakes

  • Using gas density instead of manometer-fluid density.
  • Forgetting that this is usually a pressure difference, not absolute pressure.

One free problem

Practice Problem

A water manometer measuring gas pressure has = 1000 kg/, h = 0.25 m, and g = 9.81 m/. What is the pressure difference?

Manometer Fluid Density1000 kg/m^3
Gravitational Acceleration9.81 m/s^2
Height Difference0.25 m

Solve for: pressureDifference

Hint: Use deltaP = g h.

The full worked solution stays in the interactive walkthrough.

References

Sources

  1. Munson, Young, Okiishi, Huebsch, and Rothmayer, Fundamentals of Fluid Mechanics, Wiley, 2013
  2. OpenStax University Physics Volume 1, Pressure Gauges and Manometers, accessed 2026-04-09
  3. NIST CODATA
  4. IUPAC Gold Book
  5. Wikipedia: Manometer
  6. Fundamentals of Fluid Mechanics by Munson, Young, and Okiishi
  7. NIST Chemistry WebBook
  8. Britannica