Hydrostatic pressure
1. Hydrostatic pressure overview
2. Hydrostatic pressure formula
3. Hydrostatic pressure vs depth of water
4. Practice problems
5. Hydrostatic pressure calculator
1. Hydrostatic Presure Overview
The hydrostatic pressure is the pressure exerted by a resting fluid. The hydrostatic pressure is due to the gravity forces acting on the fluid.
2. Hydrostatic Pressure Formula
The pressure exerted only by the liquid, without considering the atmospheric pressure / pressure above the liquid is ρ.g.h. The Hydrostatic pressure calculation formula is then following : ρ.g.h
It is however important to understand that there is also a pressure above the liquid that needs to be considered. The total pressure at depth h, considering the pressure above the liquid plus the hydrostatic pressure is the following : p = pa + ρ.g.h
With :
pa=Pressure above the liquid (Pa)
p=Pressure at the point of calculation (Pa)
ρ=Volumic mass of the liquid (kg/m3)
h=Height of liquid (m)
g=gravity acceleration (m.s-2)
g=9.81 m.s-2
3. Hydrostatic pressure vs depth of water
The calculation is done assuming a density of water constant and equal to 1000 kg/m3.
| Depth of water | Hydrostatic Pressure (bar) |
| 0 | 0 |
| 5 | 0.4905 |
| 10 | 0.981 |
| 15 | 1.4715 |
| 20 | 1.962 |
| 25 | 2.4525 |
| 30 | 2.943 |
| 35 | 3.4335 |
| 40 | 3.924 |
| 45 | 4.4145 |
| 50 | 4.905 |
| 55 | 5.3955 |
| 60 | 5.886 |
| 65 | 6.3765 |
| 70 | 6.867 |
| 75 | 7.3575 |
| 80 | 7.848 |
| 85 | 8.3385 |
| 90 | 8.829 |
| 95 | 9.3195 |
| 100 | 9.81 |
4. Practice problems
What is the pressure exerted by water at a depth of 4 m, with a water at 12 degrees celcius ?
Step 1 : Calculate the density of water at 12 degrees celcius
The density of water is 1007 kg/m3 at this temperature
Step 2 : Calculate the hydrostatic pressure thanks to the formula ρ.g.h
P = ρ.g.h = 1007*9.81*4 = 39516 Pa = 0.395 bar
5. Hydrostatic pressure calculator
The hydrostatic pressure calculator can be downloaded here : Hydrostatic Pressure calculator Excel
Warning : this calculator is provided to illustrate the concepts mentioned in this webpage, it is not intended for detail design. It is not a commercial product, no guarantee is given on the results. Please consult a reputable designer for all detail design you may need.
