Hydrostatic Pressure Calculator — Fluid Depth Pressure
Find the pressure at any depth in a fluid — fresh water, seawater, mercury, or a custom density. Enter depth and fluid type to get gauge and absolute pressure in Pa, kPa, bar, and atmospheres, with a pressure-vs-depth chart.
Fluid
m
m/s²
Pressure above atmospheric due to the fluid column alone
- 1
Gauge pressure (Pa)
ρ × g × h = 1,000 × 9.81 × 10 = 98,100Weight of the fluid column per unit area above the point. - 2
Gauge pressure (kPa)
98,100 ÷ 1 000 = 98.100
How does this calculator work?
P = ρgh gives gauge pressure in Pascals: density ρ (kg/m³) × g (9.81 m/s²) × depth h (m). Absolute pressure = P_gauge + 101 325 Pa. Fresh water adds roughly 9.81 kPa per metre. The pressure-vs-depth relationship is linear for incompressible fluids.
Formula
How this is calculated
Hydrostatic pressure is the pressure exerted by the weight of a static fluid column above a given point. It depends on three quantities: fluid density ρ (kg/m³), gravitational acceleration g (m/s²), and depth h (m). The formula P = ρgh gives the gauge pressure — the excess above atmospheric. For example, every 10 m of fresh water adds roughly 98.1 kPa of pressure, approximately one additional atmosphere.
Absolute pressure is the gauge pressure plus atmospheric pressure at the surface, taken here as 101 325 Pa (1 standard atmosphere, valid at sea level). The chart shows the linear relationship between pressure and depth, which holds well for liquids because they are nearly incompressible at ordinary depths. For gases the density changes with pressure, so P = ρgh does not apply over large altitude differences.
Practical notes: g varies slightly with latitude (9.78–9.83 m/s²) and altitude. At great ocean depths, water density increases slightly with compression; this calculator assumes constant density. For pressures beyond a few hundred metres, specialist calculations accounting for compressibility and temperature are used.
Frequently asked questions
P = 1000 × 9.81 × 10 = 98 100 Pa ≈ 98.1 kPa gauge, about 1 additional atmosphere. Absolute pressure ≈ 199.4 kPa ≈ 1.97 atm.
The weight of fluid above a point grows proportionally with depth at constant density. Each additional metre of fresh water adds approximately ρg = 1000 × 9.81 ≈ 9 810 Pa (≈ 0.097 atm).
Gauge pressure is measured relative to atmospheric pressure (zero at the surface). Absolute pressure is gauge pressure plus atmospheric (≈ 101 325 Pa). Scuba depth gauges show gauge pressure; engineering systems often require absolute.
TG we-Calculate Editorial Team. (2026). Hydrostatic Pressure Calculator — Fluid Depth Pressure [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/hydrostatic-pressure-calculator
TG we-Calculate Editorial Team. "Hydrostatic Pressure Calculator — Fluid Depth Pressure." TG we-Calculate. 2026. https://we-calculate.com/calculator/hydrostatic-pressure-calculator.
TG we-Calculate Editorial Team, "Hydrostatic Pressure Calculator — Fluid Depth Pressure," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/hydrostatic-pressure-calculator
@misc{wecalculate_hydrostatic_pressure_calculator, title = {Hydrostatic Pressure Calculator — Fluid Depth Pressure}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/hydrostatic-pressure-calculator}}, year = {2026}, note = {TG we-Calculate} }
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