Manometer Pressure Reading Calculator

About this calculator

A liquid-column manometer measures pressure by the height a fluid rises or falls in a tube connected to the system being measured. The reading follows the hydrostatic pressure formula P = ρ × g × h, where ρ is the fluid's density, g is gravitational acceleration (9.81 m/s²), and h is the height difference between the two fluid columns — a taller column of a denser fluid like mercury (ρ ≈ 13,534 kg/m³) registers a much larger pressure than the same height of water for the same applied pressure, which is exactly why mercury is used for compact manometers.

This calculator converts a raw column-height reading into pressure in Pascals, kilopascals, and millimeters of mercury (mmHg), the traditional unit still used for blood pressure and barometric readings. HVAC technicians measuring duct static pressure, chemistry and physics lab instructors, and process engineers use manometers and this formula whenever a direct, calibration-free pressure reading is needed — no electronic sensor required.