Pressure Calculator (P = F/A)
By Santaji GadepatilinUpdated October 27, 2026
Pressure is force spread over an area. It explains why sharp knives cut and why wide tyres don't sink, and it is one of the most measured quantities in industry — see absolute vs gauge pressure, Pascal's law in pressure instruments and the U-tube manometer.
How to use the pressure calculator
Enter the force and the area it acts on. The pressure appears in kPa, bar, psi or any pressure unit. You can also find the area needed to keep pressure below a limit.
Pressure formula
P = F ÷ A
Worked example
A 70 kg person (about 700 N) standing on two feet covering 400 cm²:
P = 700 ÷ 0.04 = 17,500 Pa = 17.5 kPa
On stiletto heels with 1 cm² each carrying half the weight, the pressure under each heel is 350 N ÷ 0.0001 m² = 3,500 kPa — 200 times higher.
Pressure examples
| Situation | Force | Area | Pressure |
|---|---|---|---|
| Person standing (two feet) | 700 N | 400 cm² | 17.5 kPa |
| Person on one stiletto heel | 700 N | 1 cm² | 7,000 kPa |
| Elephant (four feet) | 50,000 N | 4,000 cm² | 125 kPa |
| Car tyre contact (each) | 3,000 N | 150 cm² | 200 kPa |
| Drawing pin point | 20 N | 0.0001 cm² | 2,000,000 kPa |
Small areas create huge pressures, which is why knives cut and pins pierce, and why snowshoes stop you sinking.
Pressure in fluids
In a liquid, pressure increases with depth:
P = ρ × g × h
10 m of water adds about 98 kPa — roughly one atmosphere. See the hydrostatic pressure calculator.
Hydraulics
Pressure applied to an enclosed liquid is transmitted equally (Pascal’s principle). A small force on a small piston creates a large force on a large piston. Car brakes, jacks and excavators use this. See the hydraulic cylinder force calculator.
Gauge vs absolute
Most gauges read pressure above atmospheric (gauge pressure). Add about 101.3 kPa to get absolute pressure at sea level.
Units
1 Pa = 1 N/m² · 1 kPa = 1,000 Pa · 1 bar = 100 kPa · 1 psi = 6.895 kPa
Frequently asked questions
What is the pressure formula?
Pressure = force ÷ area. One pascal is one newton per square metre.
Why do sharp knives cut better?
The same force on a much smaller area creates much higher pressure.
Why do snowshoes work?
They spread your weight over a larger area, lowering the pressure so you don't sink.
What is the SI unit of pressure?
The pascal (Pa), equal to one newton per square metre.
How do I convert kPa to psi?
Divide by 6.895. 200 kPa is about 29 psi. Use the pressure converter for other units.