Water Pressure at Depth Calculator — Hydrostatic Pressure
Find the absolute and gauge pressure at any depth in fresh water, seawater or mercury. Results in pascals, bar, atm, MPa and psi — with a diving-reference range meter.
m
Fluid
Pa
P = P₀ + ρ × g × h (g = 9.806 65 m/s²)
- 1
Gauge pressure (ρ × g × h)
1,000 × 9.807 × 10 = 98,067g = 9.806 65 m/s²; result in pascals. - 2
Absolute pressure (P₀ + gauge)
101,325 + 98,067 = 199,392
How does this calculator work?
Hydrostatic pressure at depth h: P = P₀ + ρgh. Fresh water (1 000 kg/m³) adds ≈ 9 807 Pa per metre — about 1 atm per 10.33 m. Seawater (1 025 kg/m³) adds 1 atm per 10.06 m. Gauge pressure = ρgh; absolute pressure adds surface pressure (usually 101 325 Pa). Results in Pa, atm, bar, MPa and psi.
Formula
How this is calculated
Hydrostatic pressure is the pressure exerted by the weight of a static fluid column above a given point. Every additional metre of fluid adds its weight per unit area: P = P₀ + ρgh, where P₀ is the pressure at the surface (typically atmospheric pressure, 101 325 Pa = 1 atm), ρ is the fluid density in kg/m³, g = 9.80665 m/s² is standard gravity, and h is the depth in metres.
The gauge pressure — the pressure in excess of the surface value — is simply ρgh. For fresh water (ρ = 1 000 kg/m³), gauge pressure increases by 9 807 Pa per metre, corresponding to roughly 1 additional atmosphere every 10.33 m. Seawater (ρ ≈ 1 025 kg/m³) gives slightly higher pressure: about 1 atm per 10.06 m. Mercury (ρ = 13 600 kg/m³) is included for manometer and barometer problems where pressure is expressed in "mm Hg".
Absolute pressure includes both the atmospheric and hydrostatic contributions and is the value required in most physical and chemical equations. Real seawater is slightly compressible at great depths (> 1 000 m), causing density to increase by a few percent, so the linear model slightly underestimates the true pressure at ocean-trench depths. The formula assumes a static, homogeneous, incompressible fluid.
Frequently asked questions
A 10 m column of fresh water exerts a pressure of 1 000 kg/m³ × 9.807 m/s² × 10 m = 98 070 Pa ≈ 0.97 atm. The approximation "1 atm per 10 m" is a useful dive-safety shorthand; the exact figure is 10.33 m for fresh water and 10.06 m for seawater.
Gauge pressure is the excess above the surrounding atmosphere (what a tire gauge reads). Absolute pressure adds the atmospheric component: P_abs = P_atm + P_gauge. Physics equations (ideal gas law, Bernoulli) require absolute pressure; most engineering pressure gauges display gauge pressure.
No. The formula assumes constant density, which is accurate to better than 1% for depths up to a few hundred metres. At ocean-trench depths (6 000–11 000 m) seawater compresses by several percent, raising the actual pressure above this linear prediction. For those depths, use a full equation-of-state model.
Also known as
TG we-Calculate Editorial Team. (2026). Water Pressure at Depth Calculator — Hydrostatic Pressure [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/water-pressure-at-depth-calculator
TG we-Calculate Editorial Team. "Water Pressure at Depth Calculator — Hydrostatic Pressure." TG we-Calculate. 2026. https://we-calculate.com/calculator/water-pressure-at-depth-calculator.
TG we-Calculate Editorial Team, "Water Pressure at Depth Calculator — Hydrostatic Pressure," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/water-pressure-at-depth-calculator
@misc{wecalculate_water_pressure_at_depth_calculator, title = {Water Pressure at Depth Calculator — Hydrostatic Pressure}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/water-pressure-at-depth-calculator}}, year = {2026}, note = {TG we-Calculate} }
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