Pressure Calculator
Pressure is defined as the perpendicular force exerted per unit area: P = F / A. The SI unit is the pascal (Pa), equal to one newton per square metre. Pressure arises in many practical contexts: tire inflation, hydraulics, structural engineering, meteorology, diving, and fluid dynamics. This calculator supports two modes. Mode 1 computes mechanical pressure from force and area, displaying results in pascals (Pa), kilopascals (kPa), megapascals (MPa), pounds per square inch (psi), atmospheres (atm), and bar. Mode 2 computes hydrostatic pressure using the formula P = rho * g * h, where rho is fluid density in kg/m³, g is gravitational acceleration (9.81 m/s²), and h is depth in metres. This is the pressure exerted by a column of fluid, used in applications ranging from scuba diving to dam engineering. Key conversions used in this calculator: 1 psi = 6,894.76 Pa; 1 atm = 101,325 Pa; 1 bar = 100,000 Pa. Results are shown to two decimal places.
Pressure: -- Pa (-- psi)
How pressure is calculated
Pressure is force divided by the area over which it acts. The same force applied to a smaller area produces higher pressure, which is why a sharp knife cuts more easily than a blunt one.
Mode 1: Mechanical pressure
P = F / A
where P = pressure (Pa), F = force (N), A = area (m²)
Mode 2: Hydrostatic pressure
P = ρ × g × h
where P = pressure (Pa), ρ = fluid density (kg/m³), g = 9.81 m/s², h = depth (m)
Unit conversions
1 kPa = 1,000 Pa
1 MPa = 1,000,000 Pa
1 bar = 100,000 Pa
1 atm = 101,325 Pa
1 psi = 6,894.76 Pa
Worked example (Mode 1)
1,000 N force on an area of 0.5 m²:
- P = 1,000 / 0.5 = 2,000.00 Pa
- In kPa: 2,000 / 1,000 = 2.00 kPa
- In psi: 2,000 / 6,894.76 = 0.29 psi
Worked example (Mode 2)
Fresh water (rho = 1,000 kg/m³) at 10 m depth:
- P = 1,000 × 9.81 × 10 = 98,100.00 Pa
- In kPa: 98.10 kPa
- In atm: 98,100 / 101,325 = 0.97 atm
Pressure calculator: frequently asked questions
What is pressure in physics?
Pressure is the force exerted perpendicularly on a unit area of surface: P = F / A, where F is force (N) and A is area (m²). The SI unit of pressure is the pascal (Pa), defined as one newton per square metre (1 Pa = 1 N/m²). Pressure is a scalar quantity, unlike force which is a vector.
What is a pascal and how does it relate to other pressure units?
The pascal (Pa) is the SI unit of pressure. Common conversions: 1 kPa = 1,000 Pa; 1 MPa = 1,000,000 Pa; 1 bar = 100,000 Pa; 1 atm = 101,325 Pa; 1 psi (pound per square inch) = 6,894.76 Pa. Atmospheric pressure at sea level is approximately 101.325 kPa (14.696 psi).
What is psi and where is it used?
Psi (pounds per square inch) is a pressure unit used primarily in the United States and the United Kingdom for measuring tire pressure, blood pressure, and hydraulic systems. 1 psi = 6,894.76 Pa. Standard atmospheric pressure is 14.696 psi. Tire pressures for passenger cars typically range from 30 to 35 psi.
What is hydrostatic pressure?
Hydrostatic pressure is the pressure exerted by a fluid at rest due to gravity: P = rho * g * h, where rho is the fluid density (kg/m³), g is gravitational acceleration (9.81 m/s²), and h is the depth below the surface (m). For fresh water (rho = 1,000 kg/m³), pressure increases by approximately 9,810 Pa (0.97 psi) for every metre of depth.
What is standard atmospheric pressure?
Standard atmospheric pressure is defined as exactly 101,325 Pa (101.325 kPa) by the International Organization for Standardization. This is equivalent to 760 mmHg, 1.01325 bar, or 14.696 psi. It represents the average air pressure at sea level and is used as a reference point for pressure measurements worldwide.
Official sources
- NIST SP 330 (2019) "The International System of Units (SI)": NIST SP 330 PDF.
- NIST SI Unit definitions: nist.gov SI units.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology. General information only.