Pressure Calculator

Calculate pressure (P = F/A)

Pressure Calculator

Enter force and area

Formula
P = F / A

What Is Pressure?

Pressure is defined as the force applied perpendicular to a surface divided by the area over which that force is distributed. It quantifies how concentrated a force is. The same force spread over a large area creates low pressure, while the same force concentrated on a tiny area creates high pressure — think of the difference between snowshoes and high heels on snow.

Pressure has applications across virtually every field of science and engineering: hydraulics, pneumatics, meteorology, medicine (blood pressure), and structural engineering. The SI unit of pressure is the pascal (Pa = N/m²), but other common units include bar, atmosphere (atm), psi (pounds per square inch), and mmHg (millimeters of mercury).

How to Use This Calculator

  1. Select the quantity to solve for: Pressure (P), Force (F), or Area (A).
  2. Enter the two known values with their units (pascals/newtons/square meters, or your preferred units).
  3. Click Calculate to see the unknown value instantly.
  4. Use Reset to clear the fields and start a new calculation.

Formula & Explanation

P = F / A F = P × A A = F / P

P = Pressure in pascals (Pa), F = Force in newtons (N), A = Area in square meters (m²). 1 bar = 100,000 Pa; 1 atm = 101,325 Pa; 1 psi = 6,894.76 Pa.

Worked Examples

Example 1 — Tire Pressure

A 1,500 kg car rests on 4 tires, each with 0.04 m² contact area. Total force = 1500 × 9.81 = 14,715 N. Pressure per tire = (14715/4) / 0.04 = 91,969 Pa ≈ 0.92 bar ≈ 13.3 psi.

Example 2 — Hydraulic Cylinder

A hydraulic system exerts 50,000 N on a piston of area 0.01 m². P = 50000 / 0.01 = 5,000,000 Pa = 50 bar.

Example 3 — Atmospheric Pressure

Earth's atmosphere exerts 101,325 Pa at sea level. On a 1 m² surface: F = P × A = 101,325 × 1 = 101,325 N ≈ 10.3 tonnes of force.

Frequently Asked Questions

What are the most common pressure units?▾
Pascal (Pa) is the SI unit. Other common units: 1 bar = 100,000 Pa, 1 atm = 101,325 Pa, 1 psi = 6,895 Pa, 1 mmHg = 133.3 Pa. Blood pressure is measured in mmHg; tire pressure in psi or bar; weather in hPa (hectopascals = millibar).
What is gauge pressure vs absolute pressure?▾
Absolute pressure is measured relative to a perfect vacuum. Gauge pressure is measured relative to atmospheric pressure — it shows how much above or below atmosphere the pressure is. A tire rated at 32 psi gauge is actually at 32 + 14.7 = 46.7 psi absolute.
What is hydrostatic pressure?▾
Hydrostatic pressure is the pressure exerted by a fluid at rest due to gravity. P = ρ × g × h, where ρ is fluid density, g is gravitational acceleration, and h is depth. Water pressure increases by about 1 bar (14.5 psi) for every 10 m of depth.
What is the difference between stress and pressure?▾
Both are force per unit area, but pressure acts equally in all directions (isotropic) and is typically used for fluids. Stress in solids can be directional — normal stress acts perpendicular to a surface, shear stress acts parallel.
How does pressure relate to Pascal's Law?▾
Pascal's Law states that pressure applied to a confined fluid is transmitted equally in all directions throughout the fluid. This is the principle behind hydraulic systems — a small force on a small piston creates the same pressure that acts on a large piston, producing a much larger output force.