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Calcimator

Seawater Density Calculator

Calculate seawater density from temperature, salinity, and pressure using a simplified UNESCO equation of state.

Inputs

°F
PSU
dbar

Results

Seawater Density

1,025.97 kg/m³

Sigma-t (σt)25.97 kg/m³
Specific Volume0 m³/kg
Sound Speed1,506.7 m/s
Thermal Expansion Coeff0 /°C
How to Use This Calculator
  1. Enter Temperature, Salinity, and Pressure.
  2. Review the Seawater Density (kg/m³) result.
  3. Use Sigma-t (σt) (kg/m³) and Specific Volume (m³/kg) to inform your decision.

How the result changes with Salinity

SalinitySeawater Density
4.21,002.34 kg/m³
151,010.61 kg/m³
271,019.82 kg/m³
381,028.29 kg/m³

What each input means

Temperature
In-situ water temperature in degrees Celsius. Ranges from -2°C (polar) to 30°C+ (tropical surface).
Salinity
Practical salinity units. Average ocean salinity is ~35 PSU. Ranges from 0 (freshwater) to 42 (Red Sea).
Pressure
Hydrostatic pressure in decibars. Approximately equal to depth in meters (100 dbar ≈ 100 m).

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    Temperature = 15, Salinity = 35, Pressure = 0 = 3 input(s) provided
  2. Calculate Seawater Density
    Seawater Density
    1025.973 = 1025.973
  3. Calculate Sigma-t
    Sigma-t
    25.973 = 25.973
  4. Calculate Specific Volume
    Specific Volume
    0.000974685 = 0.000974685

Engine last updated . Checked against 4 independently-derived tests — how we verify calculators.

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