Calculate pressure at depth P = P₀ + ρgh for any liquid. Converts to kPa, atm, psi, bar, and mmHg with force on surfaces.
Hydrostatic pressure is the pressure exerted by a fluid at rest due to gravity. At any point within a static fluid, the pressure increases linearly with depth according to the fundamental equation P = P₀ + ρgh. This principle, rooted in Pascal's law, is essential for diving safety, dam design, submarine engineering, and water-supply systems.
The gauge pressure ρgh tells you how much pressure the fluid column itself adds above the surface pressure P₀. At 10 meters of freshwater depth, gauge pressure is about one atmosphere (≈ 101 kPa), which is why scuba divers double the absolute pressure on their bodies with every 10 m descent. At the bottom of the Mariana Trench (≈ 11 000 m), the pressure exceeds 1 100 atm.
This calculator handles any liquid — from freshwater and seawater to mercury, oil, blood, and custom fluids. It outputs pressure in six unit systems and computes the total force on a submerged flat surface, useful for tank wall and bulkhead design.
Whether you are sizing a water tank, planning a dive, or designing a submarine hull, knowing the pressure at depth is critical. This calculator gives instant results in all common pressure units and includes force calculations for structural design. The note above highlights common interpretation risks for this workflow. Use this guidance when comparing outputs across similar calculators. Keep this check aligned with your reporting standard.
Hydrostatic Pressure: P = P₀ + ρgh Where: • P = absolute pressure at depth (Pa) • P₀ = surface or atmospheric pressure (Pa) • ρ = fluid density (kg/m³) • g = gravitational acceleration (m/s²) • h = depth below surface (m) Gauge Pressure: P_gauge = ρgh Force on flat surface: F = P × A
Result: 3 115 kPa (≈ 30.7 atm)
P = 101 325 + 1025 × 9.81 × 300 = 101 325 + 3 016 575 = 3 117 900 Pa ≈ 3 118 kPa ≈ 30.8 atm. A submarine at 300 m depth experiences roughly 31 times atmospheric pressure.
Use consistent units, verify assumptions, and document conversion standards for repeatable outcomes.
Most mistakes come from mixed standards, rounding too early, or misread labels. Recheck final values before use. ## Practical Notes
Use this for repeatability, keep assumptions explicit. ## Practical Notes
Track units and conversion paths before applying the result. ## Practical Notes
Use this note as a quick practical validation checkpoint. ## Practical Notes
Keep this guidance aligned to the calculator’s expected inputs. ## Practical Notes
Use as a sanity check against edge-case outputs. ## Practical Notes
Capture likely mistakes before publishing this value. ## Practical Notes
Document expected ranges when sharing results.
In the deepest part of the Mariana Trench (≈ 10 994 m), the absolute pressure is about 1 100 atm or 110 MPa. Only specially engineered vessels can survive such forces.
No. Hydrostatic pressure depends only on depth, fluid density, and gravity — not on container shape. This is the "hydrostatic paradox": a narrow tube and a wide tank at the same depth have the same pressure.
Gauge pressure tells the diver how much more pressure they experience compared to the surface. Each 10 m of seawater adds roughly 1 atm of gauge pressure, affecting gas absorption and decompression requirements.
Engineers calculate the force on the dam face by integrating ρgh over the submerged area. Because pressure increases with depth, the resultant force acts at ⅓ of the depth from the bottom, not at the centre.
For most liquids over moderate depth ranges, incompressibility is an excellent approximation. In very deep ocean scenarios, seawater compressibility slightly increases density and pressure beyond the linear model.
The hydrostatic equation applies to fluids at rest. For moving fluids, Bernoulli's equation accounts for both static and dynamic pressure components.