Hydrostatic Pressure CalculatorFree online other calculator — instant results, no sign-up
Calculate gauge pressure below a fluid surface.
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About the Hydrostatic Pressure Calculator
The Hydrostatic Pressure Calculator calculates the gauge pressure produced by a stationary fluid at a specified depth below its surface. It uses fluid density and vertical depth with standard gravity to report pressure in kilopascals. With the default density of 1000 kg/m³ and depth of 5 m, the result is 49.03325 kPa.
- Fluid density (kg/m³)
- The fluid's mass per unit volume in kilograms per cubic meter, with a default of 1000 kg/m³.
- Depth (m)
- The vertical distance below the fluid surface in meters, with a default of 5 m.
Formula and method
p_g = ρgh / 1000 = (1000 × 9.80665 × 5) / 1000 = 49.03325 kPa
- p_gHydrostatic gauge pressure in kilopascals, assuming the fluid surface is at atmospheric pressure.
- ρFluid density in kilograms per cubic meter (kg/m³).
- gStandard gravitational acceleration, fixed at 9.80665 m/s².
- hVertical depth below the fluid surface in meters (m).
Multiply fluid density by standard gravitational acceleration and vertical depth to obtain pressure in pascals, then divide by 1000 to convert to kilopascals. For the default inputs, 1000 × 9.80665 × 5 gives 49033.25 Pa, which converts to 49.03325 kPa.
Worked example
These are the calculator's starting values and the results it actually produces for them.
Inputs
- Fluid density1000 kg/m³
- Depth5 m
Results
- Result49.03325 kPa
How to use the Hydrostatic Pressure Calculator
- 1Enter the fluid density in kg/m³; the default is 1000.
- 2Enter the vertical depth below the fluid surface in meters; the default is 5.
- 3Check that density is positive and depth is nonnegative, and that depth is not a distance measured along a sloped path.
- 4Run the calculation to obtain hydrostatic gauge pressure in kPa.
- 5Read the result: with the default inputs, the pressure is 49.03325 kPa above the pressure at the surface.
Reading your result
The Result row shows the pressure increase caused by the fluid column, expressed in kPa. The default result of 49.03325 kPa means the pressure at 5 m depth exceeds the surface pressure by that amount. For a surface exposed to the atmosphere, this is gauge pressure; it does not include atmospheric pressure and is not absolute pressure.
Limitations
The calculation assumes a stationary fluid with uniform density and uses fixed standard gravity of 9.80665 m/s². It does not account for flow effects, pressure surges, density changes with depth, or separate fluid layers. Temperature and salinity effects are included only through the density you enter. If the surface is pressurized rather than open to the atmosphere, the result is only the pressure increase below that surface; add the surface gauge pressure to obtain total gauge pressure. Displayed decimal places do not imply equivalent accuracy in the input measurements.
Common questions
Does the result include atmospheric pressure?+
No. For an open fluid surface, the result is gauge pressure relative to the atmosphere. Add the local atmospheric pressure, in the same units, to obtain absolute pressure.
Can I use this calculator for fluids other than water?+
Yes. Enter the density of the fluid at the relevant conditions. The default 1000 kg/m³ is a common approximation for water, not a universal fluid density.
Should I enter vertical depth or the length of a submerged pipe?+
Enter vertical depth below the surface. Hydrostatic pressure depends on vertical fluid height, not pipe length, container shape, or the distance along a slope.
Why do the default inputs give 49.03325 kPa?+
The calculator uses standard gravity of 9.80665 m/s². Multiplying 1000 kg/m³ by 9.80665 m/s² and 5 m gives 49033.25 Pa; dividing by 1000 gives 49.03325 kPa.
Does the calculator save my information?+
Calculations run in your browser. While signed in, inputs and results are automatically recorded in account history; saving a result creates a separate saved record.
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Results are estimates for informational purposes and are not financial, medical or legal advice.