Four calculators, one panel.
Solids, liquids, gases, units — pick a mode below. Everything recalculates live as you type, and every result explains itself.
Two knowns in, the third comes out — with the working shown.
The push or press, straight into the surface — a 100 kg person weighs ≈ 981 N on Earth.
The area it spreads over — a shoe sole, a tire patch, a table top.
Any unit — it converts through pascals (SI) automatically.
Density ρ — the heavier the liquid, the faster pressure builds with depth.
In kilograms per cubic metre — water ≈ 1000, mercury ≈ 13,600.
Straight down from the surface to the point you care about.
9.81 on Earth, 1.62 on the Moon, 3.71 on Mars.
Gauge is what a meter reads; absolute adds the air's 101.325 kPa on top.
1 mol ≈ 6.022×10²³ molecules. Starting from a mass? Divide by molar mass — 4 g of helium = 1 mol.
The container's volume — 22.414 L is the classic one-mol volume at 0 °C and 1 atm.
Converted to kelvin automatically — K = °C + 273.15.
Type any pressure and pick its unit.
The headline result uses this unit — every other unit follows in the full table.
Question to answer in four steps.
No setup, no sign-up — the calculator starts working the moment the page loads. Here is the whole workflow.
Pick your mode
Four tabs cover the four everyday questions: force over an area, pressure at depth, gas in a container, and plain unit conversion. They share one results panel, so there's nothing new to learn after the first click.
Enter what you know
Every input takes its own unit — newtons or pound-force, metres or feet, pascals or psi. Everything converts through SI behind the scenes, so mixed units are never a trap. The example chips fill in real-world cases in one tap.
Read the live answer
Results update as you type. The big number is the headline value, the rows below convert it to the units you'll actually meet in class or a spec sheet, and the formula box shows your own numbers substituted into the equation.
Copy it or keep going
One tap on COPY puts the whole result set — value, conversions and the worked formula — on your clipboard for notes or homework. Switch modes or flip gauge to absolute without losing your inputs.
The formulas behind the numbers.
Every result the calculator shows is one of these lines doing the work — here they are, so you can check it by hand.
Contact pressure
The defining formula: force perpendicular to a surface, divided by the area it's spread over. Newtons over square metres give pascals — halve the area and you double the pressure.
Hydrostatic pressure
The pressure a liquid column of density ρ and height h exerts at its base. Fresh water adds 9.81 kPa for every metre of depth — roughly one atmosphere per 10 m.
Gauge vs absolute
Gauge pressure reads zero in open air. Add the atmosphere's 101.325 kPa to get absolute pressure — the number that matters for physics, not just for tire gauges.
Ideal gas law
Rearranged, pressure = nRT ÷ V. Temperature must be kelvin, volume cubic metres, and R = 8.314 J/(mol·K) — then 1 mol at 0 °C in 22.414 L lands on one atmosphere.
The pascal
One newton spread over one square metre. It's tiny — a sheet of paper resting on a table presses with about 1 Pa — which is why kPa, bar and psi do most of the everyday work.
Boyle's law
Squeeze a fixed amount of gas at constant temperature and pressure trades with volume: half the volume, double the pressure. It's the ideal gas law with n and T held still.
Pressure, answered.
The questions that come up most when pressure homework stops cooperating. If yours isn't here, the formulas section above — or the calculator itself — probably covers it.
What is the formula for pressure?+
Pressure is force spread over area: P = F ÷ A. Take the force acting perpendicular to a surface, divide by the area it acts on, and the answer is in pascals — the SI unit defined as exactly 1 N/m².
Example: 500 N resting on 0.05 m² of table gives P = 500 ÷ 0.05 = 10,000 Pa = 10 kPa.
How do I calculate pressure from force and area?+
Measure or estimate the force in newtons and the contact area in square metres, then divide. A 500 N person stepping on a 1 cm² (0.0001 m²) high-heel tip produces 5,000,000 Pa ≈ 725 psi, while the same force on a 0.07 m² elephant foot gives only about 214,000 Pa — same force, very different pressure.
Mode 01 of the calculator does this, and can also reverse-solve for force or area.
What is the difference between gauge and absolute pressure?+
Gauge pressure is measured relative to the atmosphere, so it reads zero at sea level. Absolute pressure is measured from a perfect vacuum: P(abs) = P(gauge) + 101.325 kPa.
A tire at 32 psi gauge is about 46.7 psi absolute. Mode 02 has a one-tap switch between the two.
How do I calculate water pressure at depth?+
Use the hydrostatic formula P = ρgh, where ρ is density (about 1000 kg/m³ for fresh water, 1025 for sea water), g is 9.81 m/s² and h is depth in metres.
Every 10 m of fresh water adds roughly 98.1 kPa ≈ 1 atmosphere — a handy rule of thumb. At 40 m, a diver feels about 392 kPa gauge from the water alone.
Which pressure units does the converter support?+
Pascals (Pa), hectopascals, kilopascals, megapascals, gigapascals, bar, millibar, atmospheres, psi, ksi, psf, mmHg (torr), inHg, mmH₂O and mH₂O.
Every conversion goes through pascals: 1 atm = 101,325 Pa exactly, 1 bar = 100,000 Pa exactly, and 1 psi = 6,894.757293 Pa.
How does the ideal gas pressure calculator work?+
It rearranges PV = nRT to P = nRT ÷ V. Enter the amount of gas in moles, the volume and the temperature; the tool converts temperature to kelvin (K = °C + 273.15) and volume to cubic metres, then uses R = 8.314462618 J/(mol·K).
One mole of gas at 0 °C in 22.414 L comes out at 101,326 Pa — essentially one atmosphere.
Why does a smaller contact area increase pressure?+
Because P = F ÷ A: the same force divided by less area gives a bigger result. That's why needles pierce, knives cut, and snowshoes keep you on top of the snow — spreading your weight over more area lowers the pressure.
Doubling the contact area halves the pressure, and vice versa.
Is this calculator free, and is my data sent anywhere?+
It is completely free and runs entirely in your browser — nothing you type is uploaded, logged, or sent to a server. No account, no sign-up, no limits.