Pounds per Square Inch Calculator

The pounds per square inch calculator enables you to easily compute pressure in psi or your preferred unit.

Pressure from the force40 kPa5.8015 psi, 0.4 bar

As atmospheres0.394769 atm

Force800 N

Area0.02 m²0.2153 ft²

Hydrostatic pressure at depth98.0665 kPa1,000 kg/m³ × 9.8067 × 10 m

Absolute pressure at depth199.3915 kPagauge pressure plus one atmosphere above

In atmospheres at depth1.9678 atm

Depth that adds one atmosphere10.3323 mabout 10 m of water — which is why pressure doubles at that depth

Force on your 0.02 m² at that depth3.9878 kN

On 50% of the area80 kPa2× the pressure for the same force

On 10% of the area400 kPa10× the pressure for the same force

The formula

P = F ÷ A; hydrostatic P = ρgh

Same force, different area

Pressure is force spread over area, so the same push produces wildly different pressures depending on how concentrated it is. This is why a sharp knife cuts and a blunt one does not, why stiletto heels damage floors that an elephant would not, and why snowshoes work. Nothing about the force changes; only its distribution does.

Hydrostatic pressure depends on depth, density and gravity — and not at all on the shape or volume of the container. A narrow pipe and a wide lake filled to the same depth exert the same pressure at the bottom, which strikes most people as wrong the first time they meet it. Roughly ten metres of water adds one atmosphere, so a diver at that depth is under twice the pressure at the surface.

Note the difference between gauge and absolute pressure. Gauge pressure is measured relative to the surrounding atmosphere and is what a tyre gauge reads; absolute pressure includes the atmosphere itself. Confusing the two is a one-atmosphere error, which matters a great deal near vacuum and rather less at depth.