Pressure Calculator — Step-by-Step Solutions

The Pressure Calculator handles all common pressure computations. Calculate pressure from force and area (P = F/A), find hydrostatic pressure at depth, convert between pressure units, or find force from pressure and area.

The calculator supports four modes: basic pressure from force and area, hydrostatic pressure using fluid density and depth, a unit converter covering Pa, kPa, atm, bar, psi, and mmHg, and reverse calculation to find force from pressure and area.

Force (N)

Area (m²)

Your calculations will appear here

How to Use the Pressure Calculator

Select a calculation mode: P = F / A, Hydrostatic, Unit Converter, or Find Force.
For P = F / A, enter the force (N) and area (m squared). The calculator divides force by area to find pressure in Pascals.
For Hydrostatic, enter the fluid density (default 1000 kg/m cubed for water), depth, and gravity. The calculator computes both the hydrostatic pressure and total pressure including atmospheric.
For Unit Converter, enter a pressure value and select its unit. The calculator converts to Pa, kPa, atm, bar, psi, and mmHg simultaneously.
For Find Force, enter pressure (Pa) and area (m squared). The calculator multiplies them to find the force.

Formula and Theory

Pressure is defined as force per unit area: P = F/A. The SI unit of pressure is the Pascal (Pa), which equals one Newton per square metre. Pressure acts perpendicular to the surface on which the force is applied.

Hydrostatic pressure is the pressure exerted by a fluid at rest due to gravity. It increases linearly with depth according to P = rho times g times h, where rho is the fluid density, g is gravitational acceleration, and h is the depth below the surface.

The total pressure at a point underwater equals the atmospheric pressure plus the hydrostatic pressure. At sea level, atmospheric pressure is approximately 101,325 Pa (1 atm).

Common pressure units include Pascals (Pa), kilopascals (kPa), atmospheres (atm), bar, pounds per square inch (psi), and millimetres of mercury (mmHg). Each has specific applications: Pa and kPa in engineering, atm in chemistry, psi in tyre pressures, and mmHg in blood pressure readings.

Worked Examples

Example 1: Basic pressure

Problem: A force of 500 N is applied over an area of 2 m squared. What is the pressure?

Solution: P = F/A = 500 / 2 = 250.

Answer: 250 Pa

Example 2: Hydrostatic pressure

Problem: What is the water pressure at a depth of 10 m? (density = 1000 kg/m cubed, g = 9.81 m/s squared)

Solution: P = rho * g * h = 1000 * 9.81 * 10 = 98100.

Answer: 98,100 Pa (about 0.968 atm)

Example 3: Unit conversion

Problem: Convert 1 atm to all common pressure units.

Solution: 1 atm = 101325 Pa = 101.325 kPa = 1.01325 bar = 14.696 psi = 760 mmHg.

Answer: See conversion table

Example 4: Find force from pressure

Problem: A pressure of 300 Pa acts on a 4 m squared surface. What is the force?

Solution: F = P * A = 300 * 4 = 1200.

Answer: 1200 N

Frequently Asked Questions

What is the difference between pressure and force?

Force is measured in Newtons and acts in a direction. Pressure is force distributed over an area (Newtons per square metre). The same force creates more pressure when applied to a smaller area.

Why does pressure increase with depth?

As you go deeper in a fluid, there is more fluid above pressing down due to gravity. The weight of this column of fluid increases with depth, creating higher pressure.

What is atmospheric pressure?

Atmospheric pressure is the pressure exerted by the weight of the atmosphere above a point. At sea level it is approximately 101,325 Pa or 1 atm. It decreases with altitude.

How do I convert between pressure units?

Use the unit converter mode. The key conversions are: 1 atm = 101,325 Pa = 1.01325 bar = 14.696 psi = 760 mmHg. All units measure the same physical quantity.

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