Fluid Pressure at Depth Calculator
Calculate hydrostatic pressure at any depth in a fluid.
Supports seawater, fresh water, mercury, and custom densities.
Shows pressure in Pa, atm, bar, and PSI.
Pressure at Depth
The pressure at depth h in a fluid is:
P = P₀ + ρgh
Where:
- P = Total pressure at depth (Pa)
- P₀ = Surface pressure (typically 101,325 Pa = 1 atm)
- ρ = Fluid density (kg/m³)
- g = Gravitational acceleration = 9.81 m/s²
- h = Depth below the surface (m)
Fluid densities:
- Fresh water: 1,000 kg/m³
- Seawater: 1,025 kg/m³
- Mercury: 13,600 kg/m³
- Ethanol: 789 kg/m³
Pressure unit conversions:
- 1 atm = 101,325 Pa = 1.01325 bar = 14.696 PSI = 760 mmHg
- 1 bar = 100,000 Pa ≈ 0.987 atm
- 1 PSI = 6,894.76 Pa
Scuba diving reference:
- Every 10 m of seawater depth adds approximately 1 atm of pressure
- At 30 m: total pressure ≈ 4 atm absolute
- At 100 m: ≈ 11 atm — requires technical diving equipment
Design implications:
- Submarine hulls must withstand thousands of PSI
- The deepest point in the ocean (Challenger Deep, 10,935 m): P ≈ 1,099 atm ≈ 16,160 PSI
- Deep-sea fish have evolved to survive these pressures with specialized adaptations