Pressure Calculator
Pressure, force and area (P = F ÷ A).
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Pressure is how much force is spread over an area. Enter any two of pressure, force, and area and this calculator finds the third, converting the result between pascals, bar, atmospheres, and psi.
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Pressure — The Quick Answer
Pressure equals force divided by area (P = F ÷ A), measured in pascals. The same force over a smaller area gives a higher pressure — which is why a sharp knife cuts more easily than a blunt one.
Shortcut
P = F ÷ A | F = P × A | A = F ÷ P
Common pressure values
| Pressure | In pascals | In other units |
|---|---|---|
| Atmospheric (sea level) | 101,325 Pa | 1 atm · 1.013 bar · 14.7 psi |
| Car tyre | ~220,000 Pa | ~32 psi |
| 1 bar | 100,000 Pa | 0.987 atm |
| Blood pressure (120 mmHg) | ~16,000 Pa | ~2.3 psi |
One pascal is one newton per square metre — a very small unit, so everyday pressures are usually quoted in kilopascals (kPa), bar, or psi.
How It Works
The Formula
Force spread over area
Formula
P = F / A F = P × A A = F / P
Variables
Pressure
Force per unit area, in pascals (Pa). 1 Pa = 1 N/m². 1 kPa = 1000 Pa; 1 bar = 100,000 Pa.
Force
The force pressing on the surface, in newtons. For weight, this is mass × gravity.
Area
The area the force acts over. Smaller area means higher pressure for the same force.
Note: This formula is for force applied perpendicular to a surface. For fluid pressure at depth, use P = ρgh (density × gravity × depth) instead.
Worked Example: 500 N Over 0.25 m²
And why area changes everything
Note force and area
F = 500 N, A = 0.25 m²
Apply P = F ÷ A
500 ÷ 0.25 = 2,000 Pa
Convert to kPa
2,000 Pa = 2 kPa
Shrink the area tenfold
Same 500 N on 0.025 m² = 20,000 Pa — ten times the pressure
Reference Guide
| Pressure | In pascals | Other units |
|---|---|---|
| Atmospheric (sea level) | 101,325 Pa | 1 atm · 1.013 bar · 14.7 psi |
| Car tyre | ~220,000 Pa | ~2.2 bar · ~32 psi |
| 1 bar | 100,000 Pa | 0.987 atm |
| 1 psi | 6,895 Pa | 0.069 bar |
What the Pressure Result Tells You
Force, area, and everyday pressure
The same force over a smaller area produces more pressure — which is why sharp knives cut and drawing pins pierce. Spread force over a larger area and pressure drops, which is how snowshoes and wide tyres avoid sinking.
Best for: Understanding the force-versus-area trade-off
One pascal is one newton per square metre — tiny, since atmospheric pressure is about 101,325 Pa. That's why everyday pressures are quoted in kilopascals, bar, or psi.
Best for: Choosing a sensible unit to read
1 bar = 100,000 Pa, 1 atm = 101,325 Pa, and 1 psi ≈ 6,895 Pa. So a tyre at 32 psi is about 2.2 bar — the same pressure in different clothes. This formula is for force perpendicular to a surface; fluid pressure at depth uses ρgh instead.
Best for: Reading tyre, weather, and gauge pressures
What Is Pressure?
Pressure is how concentrated a force is — force divided by the area it acts on, P = F ÷ A, measured in pascals (one newton per square metre). The same force over a smaller area gives higher pressure, which is why a sharp knife cuts more easily than a blunt one and why a person lying flat on thin ice is safer than standing. Because the pascal is small, everyday pressures use kilopascals, bar, or psi — atmospheric pressure is about 101,325 Pa. This calculator solves for pressure, force, or area and reports the result across Pa, kPa, bar, atm, and psi. (For pressure at depth in a fluid, use P = ρgh instead.)
Key Features
💡 Pro Tips
- →Convert area to square metres before dividing, or use the unit selector so the tool does it for you.
- →To cut pressure, spread the force over more area; to increase it, concentrate the force onto less.
- →A tyre gauge reads 'gauge pressure' (above atmospheric); absolute pressure is that plus about 101 kPa.
- →This formula is for force pressing on a surface — for liquid pressure at a depth, use density × gravity × depth.
Common Mistakes
Leaving area in cm² when using newtons
Pascals require area in square metres. Dividing newtons by cm² gives a figure 10,000× too large. Convert to m² first.
Confusing the pressure units
1 bar, 1 atm, and 1 psi are very different sizes. Mixing them up (e.g. treating psi as kPa) throws results off badly — the tool shows all of them to avoid this.
Using P = F/A for fluid depth pressure
Pressure from a column of liquid depends on depth, density, and gravity (P = ρgh), not a simple force over area. Use the right relationship for the situation.
Research & Citations
Sources and standards referenced for the factual claims on this page
- [1]
Bureau International des Poids et Mesures (BIPM) (2019). The International System of Units (SI) — definition of the pascal. BIPM.
SI definition of the pascal (1 Pa = 1 N/m²).
View source - [2]
National Institute of Standards and Technology (NIST) (2023). Standard atmospheric pressure and pressure unit conversions. NIST.gov.
Reference values for atmospheric pressure and unit conversions.
View source
This calculator is a reference tool, not a substitute for professional advice. Verify important health, financial, legal, or safety decisions with a suitably qualified professional.
Last updated: October 7, 2026
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Frequently Asked Questions
How do I calculate pressure?
Divide force by area: P = F ÷ A. A 500 N force spread over 0.25 m² gives 500 ÷ 0.25 = 2000 Pa (2 kPa).
What is one pascal?
One pascal (Pa) is one newton of force per square metre. It's a small unit — atmospheric pressure is about 101,325 Pa — so pressures are often given in kilopascals, bar, or psi.
Why does a smaller area increase pressure?
Because pressure is force divided by area. Keeping the force the same but shrinking the area raises the pressure. That's why sharp knives, needles, and high heels concentrate force into tiny areas.
How do I convert between pressure units?
This calculator does it automatically: 1 bar = 100,000 Pa, 1 atm = 101,325 Pa, and 1 psi ≈ 6,895 Pa. Enter a pressure in any unit and the result shows all of them.