Hydrostatic Pressure Calculator

Type density ρ and depth h. The calculator computes p = ρ g h. 1000 kg/m³ and 10 m of water is about 98 kPa. Empty g = 9.81.

Buoyancy of that fluid: F = ρ V g. Density: ρ = m/V.

Inputs

Result

Density ρ (kg/m³), Depth h (m) and g (m/s², optional). The result shows up here.

How it works

h p = ρ·g·h Pa = N/m²
Hydrostatic pressure grows with depth h in a liquid of density ρ.

p = ρ g h grows with depth. Water 1000 kg/m³ and h = 10 m: p = 98,100 Pa, about 98 kPa. At 2 m that is 19,620 Pa ≈ 19.6 kPa. At 5 m about 49 kPa. At 30 m about 294 kPa. At 50 m about 491 kPa. Seawater 1025 kg/m³ and 100 m give about 1.01 MPa. Oil 900 kg/m³ and 3 m give about 26.5 kPa.

That is the fluid-column pressure, above atmosphere at the surface if you count the column alone. For absolute p, add about 101 kPa from outside. A barometer scale: ρ ≈ 13,550 kg/m³ and h = 0.76 m give about 101 kPa, the order of one atmosphere. The calculator does not add atmosphere on its own.

Fields: ρ in kg/m³, h in meters, empty g = 9.81. Result in pascals, 1 Pa = 1 N/m². A comma and a period are the same h: 2,5 and 2.5. Typed 0 in ρ or h gives p = 0. ρ and h both need a number before 98 kPa can appear.

Buoyancy F = ρ V g is on the neighbouring page: a force in newtons from volume, not pressure from depth. A liter of water is still 9.81 N of buoyancy, whether or not p at 10 m is 98 kPa. Mechanical p = F/S is on the force-and-area pressure page.

ρ = m/V is on the density page when the problem gives mass and volume of the fluid. Here ρ is an input. The model is hydrostatic, no flow and no waves.

Type 1000 and 10, click Calculate, and match about 98 kPa. Then 2 m and see 19.6 kPa. The header symbol does not dive.

How to use

  1. Type ρ, for example 1000 for water or 1025 for seawater.
  2. Type h in meters, for example 10. That is column depth, not volume.
  3. Leave g blank for Earth (9.81), or type g from the problem.
  4. Click Calculate. 10 m of water gives 98,100 Pa ≈ 98 kPa. 2 m gives about 19.6 kPa.
  5. For buoyancy, open F = ρ V g. For p = F/S, open the force-and-area pressure page.

Formula

p = ρ · g · h

Default g = 9.81 m/s2. Unit: Pa = N/m2.

p, ρ, g, and h in a fluid column

Hydrostatic pressure here is p = ρ g h. Depth h from the free surface, not from the tank floor. 1000 kg/m³ at 1 m and 9.81 is 9810 Pa.

p
Pressure in pascals: Pa = N/m². At 2 m of water, p ≈ 19.6 kPa, twice 9810 Pa.
ρ
Fluid density in kg/m³. Water ≈ 1000. Do not type a body mass or a force F here.
g
Optional, blank = 9.81. It enters p = ρ g h, unlike ρ = m/V on the density card.
h
Depth in meters from the free surface. Zero meters gives p = 0 gauge from the column.

Real-life examples

Example 1

ρ = 1000 kg/m³, h = 10 m, blank g → p ≈ 98 kPa.

Example 2

h = 2 m in water.

Example 3

h = 30 m, water.

Example 4

ρ ≈ 1025 kg/m³, h = 100 m.

Example 5

h = 5 m, typed g.

Example 6

ρ ≈ 13550 kg/m³, h = 0.76 m (barometer scale).

Example 7

ρ = 900 kg/m³, h = 3 m.

Example 8

h = 50 m at the base.

Example 9

h = 0.4 m.

Example 10

Same water, h = 10 m, g = 1.62.

Ways to use this calculator

  • You estimate p at 10 m in a pool.
  • You compare 2 m and 10 m: 19.6 kPa versus 98 kPa.

Related calculators

Pressure p = F/S
Contact pressure beside liquid-column pressure.
Potential energy
Potential energy at the same height and the same g.
Force F = m·a
Weight near Earth’s surface, from mass and g.
Density Calculator
Density: sample mass divided by its volume.
Buoyant Force Calculator
Buoyant force on the volume you immerse.

All physics calculators

Frequently asked questions

How much p at 10 m of water?

p = 1000 × 9.81 × 10 = 98,100 Pa ≈ 98 kPa. At 2 m that is about 19.6 kPa.

Is this buoyancy?

Buoyancy is F = ρ V g in newtons. Here p is in pascals from depth. A liter of water is still 9.81 N.

Which units do I type?

ρ in kg/m³, h in meters, g in m/s². Result in Pa. 1000 Pa = 1 kPa.

Do I have to type g?

Empty g = 9.81 m/s². Type g when the problem leaves Earth.

Does this include atmosphere?

The calculator computes ρ g h, the column alone. For absolute p, add about 101 kPa from outside.

How much at 100 m of seawater 1025 kg/m³?

p ≈ 1.01 MPa. For oil 900 kg/m³ and 3 m, about 26.5 kPa.

What about 0.76 m of mercury at 13,550 kg/m³?

p ≈ 101 kPa, the order of one atmosphere on a barometer scale.

Does a comma in 2.5 m work?

Yes. 2,5 and 2.5 mean the same h [m]. Pressure is ρ g h at that depth.

Where is p = F/S?

On the pressure page from force and area. Here density and depth, not F and S.

Where is ρ = m/V?

On the density page. Here ρ is an input, then p = ρ g h.

Knowledge sources

The formula is the school one. Units follow SI; NIST SP 330 and BIPM define the measures, not your result.

Page updated in 2026.