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Physics Calculators

Free physics calculators for mechanics, electricity, thermodynamics, friction, and more. Step-by-step solutions with formulas.

1 calculator
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Physics calculators handle the arithmetic so you can stay focused on the physics. Whether you're computing pressure from force and area, working out hydrostatic pressure at depth, or converting between pascals, psi, bar, and atmospheres, the tools here use the SI definitions and CODATA values for physical constants — not textbook approximations.

Every calculator shows the underlying formula and the units it expects. Inputs default to SI (meters, kilograms, seconds, pascals, newtons) but you can typically work in imperial or engineering units too — the calculator handles the conversion internally and shows both forms in the output. Useful for students, engineers, and anyone who needs a quick sanity check.

Available physics calculators

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Pressure Calculator

Calculate pressure from force and area, hydrostatic fluid pressure, and convert between pascals, psi, bar, atm, mmHg, torr, and 9 more pressure units.

Physics calculators — frequently asked questions

What is pressure in physics?
Pressure is force divided by the area it acts on: P = F/A. The SI unit is the pascal (Pa), defined as 1 N/m². A force of 10 N spread over 1 m² gives 10 Pa; the same force concentrated on 1 cm² gives 100,000 Pa. This is why a sharp knife cuts more easily than a blunt one — same force, much smaller area, much higher pressure.
How do you calculate 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 (9.80665 m/s² on Earth), and h is depth below the surface. For water (ρ = 1000 kg/m³), each 1 m of depth adds roughly 9,807 Pa or about 10 kPa. At 10 m underwater, you're experiencing about 1 atmosphere of additional pressure on top of atmospheric.
What's the difference between absolute and gauge pressure?
Gauge pressure is measured relative to local atmospheric pressure (so atmospheric = 0 gauge); absolute pressure is measured relative to a perfect vacuum (so atmospheric = ~101.325 kPa). A tire pressure gauge reading 30 psi means 30 psi above atmospheric — actual absolute pressure inside the tire is roughly 44.7 psi. Vacuum gauges work the opposite way, reading the pressure deficit below atmospheric.
Why is standard atmospheric pressure 101.325 kPa?
It's a defined value, not a measured one. The standard atmosphere (atm) was set at 101325 Pa exactly in 1954 to match the average sea-level pressure under specific reference conditions (15°C, dry air). Actual atmospheric pressure varies with weather and altitude. In other units: 1 atm = 760 mmHg = 14.696 psi = 1.01325 bar.