What is the formula for pressure?

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pohnpei397's profile pic

pohnpei397 | College Teacher | (Level 3) Distinguished Educator

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The formula for pressure is

P = F/A

In this equation, P stands for pressure while F stands for force and A stands for area.  Pressure is typically measured in a unit called the Pascal.

So what this means is that the amount of pressure that is exerted on an area is determined by the size of that area and by the amount of force that is pressing against it.

Therefore, if you have a given amount of force, you will have more pressure if it presses down on a small area than if it presses down on a large area.

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Wiggin42's profile pic

Wiggin42 | Student, Undergraduate | (Level 2) Valedictorian

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The formula for pressure is: 

P = F/A 

where P is pressure, F is force and A is area. 

The SI  unit for pressure is the Pascal  ( Pa ) which stands for:  `N/m^2`

`<span style="font-size: 14px;">The standard system uses psi or pounds per square inch. </span>`

`<span style="font-size: 14px;">Torr and mm Hg (read: millimeter Mercury) are also pressure units. </span>`

`<span style="font-size: 14px;">Atm is also a unit of pressure and as you can guess is </span>`equivalent to the pressure of Earth's atmosphere. 

To convert between the major units: 

1 Atm = 101 kPa = 760 Torr = 760 mm Hg = 14.5 psi

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rachellopez | Student, Grade 12 | (Level 1) Valedictorian

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"Pressure is defined as force per unit area." The formula for pressure is `P = (F)/(A)`, which stands for `Pressure = (Force)/(Area)`. You could use this formula for many different things, but one example would be the difference in force between an object placed at different angles. There is a photo on the website I linked below.

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jess1999 | Student, Grade 9 | (Level 1) Valedictorian

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The formula for pressure is P = F / A

F  = Force that is applied

A = Total area of the subject or also known as surface area

P = pressure

Ex:Calculate the pressure produced by a force of 900 N acting on an area of 3.0 m2


=300 Pa

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giorgiana1976 | College Teacher | (Level 3) Valedictorian

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Pressure (symbol: p) is the force applied per unit area,  in the direction perpendicular to that surface.

P=F/A, where, F is the normal force, A is the area.

Pressure is a scalar, which in IS is measured in pascals.

1 Pa = 1 N/m2

The pressure is transmitted to surrounding areas or sections of the field of fluid, in the normal direction at any point in these areas or sections.

It is a fundamental parameter in thermodynamics and is a joint variable to volume.

Characteristic Cases

Static pressure

Static pressure, usually denoted SP, is the inner pressure of a fluid which is measured with a device that moves with the same speed as the fluid. For example, to the walls of a pipeline is carried the static pressure of fluid flowing through it.

Dynamic Pressure

Dynamic pressure is the additional pressure of a fluid that would hit an area and would be forced to consume completely it's kinetic energy. It is expressed by the relation:

p dynamic= rho*(v^2/2)

where rho is fluid density in kg/m^3, v is velocity in m / s.

Stagnation pressure

Stagnation pressure is the pressure that would exert a fluid in motion if it were forced to stop. If a fluid moves faster, its stagnation pressure increases. Static pressure and stagnation pressure are related to Mach number of fluid. See also Bernoulli's equation, which however is  valid only for incompressible fluids.Pressure of a fluid in motion can be measured with a Pitot tube, connected to a manometer.

 Hydrostatic pressure

Hydrostatic pressure is the pressure due to the weight of a fluid.



ρ (rho) is density of the fluid (eg water density is almost 1000 kg/m3);

g is the acceleration due to gravity (conventional, 9.80665 m/s2 to the sea surface);

h is the height of column of liquid (in meters).

Pressure of explosion or deflagration

Explosion or deflagration pressures are created by igniting explosive gas, aerosol, suspension in closed or open spaces. These pressures propagate as a wave of shock.

Negative pressures

While pressures are generally positive, in some cases negative pressures are meet:

-When discussing the relative pressures. For example, an absolute pressure of 80 kPa may be expressed as a relative pressure of -21 kPa (ie 21 kPa under atmospheric pressure of 101 kPa). The technique is called "a depression of 21 kPa.

- When attractive forces (eg Van der Waals forces) between particles of fluid, exceeds the forces of rejection. This scenario, however, is unstable because the particles are closer and closer until rejection forces would balance the forces of attraction.

- Negative pressures occurring during plant transpiration.

-Casimir effect can create small forces of attraction by interacting with vacuum energy. Sometimes this is called 'vacuum pressure' (not to be confused with depression).

- Depending on the reference system to surface orientation, a positive pressure on one side of a surface can be considered negative on the other side of the area.

- In cosmology( dark energy, expansion of the universe).

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neela | High School Teacher | (Level 3) Valedictorian

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Pressure is defined as the normal force per unit area of a surface. If F is the force acting normal to the surface area A,then the pressure P is given by :

P = F/A, Newtons/square meter or P = F/A Pascals.

According to the dimensional analysis of the pressure from this definition is: Force/Area = [M^1]*[L^1][T^(-2)]/[L^2]

= [M^1][L^(-1)][T^(-2)], where M  represents mass, L represents length and T represents time in fundamental  standard units.




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mkcapen1 | Middle School Teacher | (Level 3) Valedictorian

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Pressure is often listed as psi.  The formula to measure pressure is Pressure equals force in pounds over the area in square inch.  The written abbreviated formula is P= F/A.

By looking at the formula one can see that top obtain the pressure on an object, one must divide the the force by the area of an object.

All fluids, liquids, and gases omit pressure.  If a fluid is not moving it exerts even pressure.  Air pressure is measured by using a barometer.

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user2630278 | eNotes Newbie

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Pressure is defined as the normal force per unit area of a surface.

If F is the force acting normal to the surface area A, then pressure P is given by:


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sid-sarfraz | Student, Graduate | (Level 2) Salutatorian

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Pressure can be defined as the force applied to in doing something. Like Peeling an apple etc.

The effects of pressure can be seen in everyday situations.

Pressure when applied;

  • a small force gives low pressure
  • a large force gives high pressure


To calculate pressure we need to measure the size of the force applied and the size of the area to which the force is applied.

Area is usually measured in square meters. where as, force is measured in Newtons (N).

In scientific terms, Pressure is the force per unit area. That can be expressed in a formula;

Pressure = Force/Area

P = F/A

Where, P= Pressure 

F = Force

A = Area

For Example;

The pressure under an elephants feet can be calculated.

Each foot has an area of about 0.2 meter power square.

It has four feet on the ground, so the total area is around 0.8m2.

The elephant weighs 50000 newtons, so this is the force. 

Pressure = Force/Area

Pressure = 50000/0.8

Pressure = 62500 N/Meter square...

PRESSURE FORMULA - As Energy Density

For measuring Pressure in a fluid or liquid, it will be taken as energy per unit volume.

Pressure = Energy/Volume

P = W/V

PRESSURE FORMULA - As Kinetic Fluid energy

Pressure = Kinetic energy/ Volume

PRESSURE FORMULA - Fluid potential energy

Pressure = Potential Energy/ Volume


To calculate pressure under our feet, we need to know the force and area, the force acts on.

Suppose Joe weighs 500N and is wearing stiletto heels which together have an area of 1 cm square (0.0001 meter square).

The pressure under Jo's bare foot would be;

Pressure = Force/Area

Pressure = 500N/0.02 meter power square

pressure = 25000 N/m2 or 25000 Pa or 25kPa

The Pressure under Jo's foot wearing heels would be;

5 000 000 N/meter square

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hardikjain | eNotes Newbie

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Pressure =  Force / Area 

SI system :

  1. Unit of force - Newton (N)
  2. Unit of area - m^2
  3. Unit of pressure - Pa
  4. 1 Pa = 1 N/m^2

Cgs system

  1. Unit of force - Dyne
  2. Unit of area - cm^2
  3. Unit of pressure - Barye 
  4. 1 Barye = 1 Dyne /cm^2

Basically pressure is directly proportional to force and inversely proportional to area.

I other words more force and less area means more pressure.

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arrellbelle | Student, College Sophomore | (Level 1) Valedictorian

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The formula for pressure is P=F/A

P = Pressure

F = Force being applied

A = (Surface) area on which the pressure is being applied to.

rimmery's profile pic

rimmery | Student, Undergraduate | (Level 1) Honors

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where P is for pressure, usually measured in Pascals

F is force, how much force you're applying 

A is for surface area upon which the pressure is being applied on

The formula states that the pressure exerted on an area is evenly distributed by the amount of force applied onto that area.

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zumba96 | Student, Grade 11 | (Level 3) Valedictorian

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The formula of pressure is force divided by area of the surface area on contact. Pressure is the force per unit area applied in a route perpendicular to the surface of an object. It is a scalar quantity denoted by the symbol p.

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alejandrogalarce | Student, Undergraduate | (Level 1) Valedictorian

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Pressure is the amount of force acting perpedicularly per unit area. The symbol of pressure is p.



p is the pressure

F is the normal force

A is the area of the surface on contact.

Pressure is a scalar quantity. It relates the vector surface element (a vector normal to the surface) with the normal force acting on it. The pressure is the scalar proportionality constantthat relates the two normal vectors.