Physics Tools
What It Does
Works out pressure from a force on an area (P = F/A) or from the depth of a fluid (P = ρgh), in whatever units suit you (Pa, kPa, bar, psi, atm, mmHg), and can solve any of these backwards — for example the area needed to stay under a pressure, or the depth at which water hits a given pressure. Everything runs in your browser.
How to Use It
- Pick a mode — force ÷ area, or a fluid column.
- Choose what to solve for, then fill in the remaining values and pick their units (or choose a fluid/planet preset).
- In fluid mode, tick Add atmosphere for absolute pressure (otherwise you get gauge pressure).
- Read the result (also shown in every pressure unit); the working is below it. Click Copy on any result.
About Pressure
Pressure is force spread over an area — P = F/A — measured in pascals (one newton per square metre). The same force feels very different depending on the area it acts on, which is why a drawing pin pierces a board (tiny area, huge pressure) while snowshoes stop you sinking (large area, small pressure). In a fluid, pressure also builds with depth: a column of fluid of density ρ pushes down with P = ρgh, so pressure rises steadily the deeper you go and depends only on the density, gravity, and depth — not on the container’s shape. Everyday pressure comes in many units: the pascal (Pa) and its multiples kPa/MPa and bar (100 kPa) in science and engineering, psi (pounds per square inch) in the US, and atm or mmHg for atmospheric and medical readings. One subtlety is gauge vs absolute pressure: a tyre gauge reads the pressure above the surrounding air (gauge), whereas absolute pressure includes the roughly 101 325 Pa (1 atm) the atmosphere already presses with — this tool lets you add that atmosphere when you want an absolute figure. Everything is computed on your device.
Example
Force mode, F = 100 N, A = 0.01 m² → P = 10 000 Pa (0.1 bar).
Frequently Asked Questions
What’s the difference between Pa, bar, and psi?
They’re all units of pressure. One bar is 100 000 Pa (close to one atmosphere); one psi is about 6895 Pa. This tool shows a pressure result in every supported unit at once, so you can read whichever you need.
What is gauge vs absolute pressure?
Gauge pressure is measured relative to the surrounding atmosphere (what a tyre gauge shows); absolute pressure adds the ~101 325 Pa of atmospheric pressure. In fluid mode, tick Add atmosphere to get absolute pressure.
Why does pressure increase with depth?
The deeper you go, the more fluid is stacked above you, and its weight presses down — P = ρgh. It depends only on the fluid’s density, gravity, and the depth, not on the shape or width of the container.
Can I solve for force, area, density, or depth?
Yes. Pick what to solve for at the top: enter the remaining values and the tool rearranges P = F/A or P = ρgh for the unknown.
Is my data sent to a server?
No. Every calculation runs locally in your browser; nothing you enter is transmitted or stored.