Pressure is defined as the force applied perpendicular to a surface divided by the area over which it acts: P = F/A. It appears everywhere in science and engineering, from atmospheric pressure to tyre inflation, hydraulic systems, fluid mechanics, and structural loading. The SI unit of pressure is the pascal (Pa), equal to one newton per square metre, but in practice you will also encounter kilopascals (kPa), megapascals (MPa), bar, atmospheres (atm), and pounds per square inch (psi). This calculator covers two modes. In the first you enter a force and an area and it returns the pressure in all five common units simultaneously. In the second mode you calculate hydrostatic or fluid pressure at a given depth: P = ρgh, where ρ is the fluid density in kg/m3, g is gravity, and h is depth in metres. This formula gives the pressure due to the weight of fluid above a point, which is the gauge pressure, the pressure above atmospheric. The default example uses a force of 1,000 N on an area of 0.25 m2, giving a pressure of 4,000 Pa (4 kPa, 0.58 psi). This is a common physics problem format: a block of known weight standing on a known base area. The fluid mode uses water (1,000 kg/m3) as its default, which makes it easy to find the pressure at any dive depth. The calculator produces all unit conversions at once, saving you from having to look up conversion factors. Results update as you type. Use this for physics homework, plumbing and hydraulics, weather and atmospheric problems, or any engineering application involving pressure.
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N
m²
kg/m³
m
m/s²
4,000 Pa
pressure
In kPa4.000 kPa
In psi0.580 psi
In bar / atm0.0400 bar / 0.0395 atm
P = F/A in pascals. Fluid mode gives gauge pressure only (pressure due to fluid above, not including atmosphere). Rounded for display.
How it works
From force and area: P = F/A in pascals. Conversions: 1 kPa = 1,000 Pa; 1 bar = 100,000 Pa; 1 atm = 101,325 Pa; 1 psi = 6,894.76 Pa. Fluid (hydrostatic gauge) pressure: P = ρgh, where ρ is density in kg/m³, g is gravity, and h is depth in metres. This gives the pressure due to the weight of fluid above the point, not including atmospheric pressure.
Worked example
A 1,000 N force is applied to a surface of area 0.25 m². Pressure = 1,000 / 0.25 = 4,000 Pa. In kPa: 4.000 kPa. In psi: 4,000 / 6,894.76 = 0.580 psi. In bar: 4,000 / 100,000 = 0.040 bar. These match the default values pre-filled above.
