This seawater freezing point calculator estimates the freezing temperature of ocean water from its salinity. Enter the salinity in parts per thousand above.
Formula (approximate)
Freezing point (°C) ≈ −0.054 × Salinity (ppt)
Example
Salinity 35 ppt (typical seawater): freezing point ≈ −0.054 × 35 = −1.89 °C.
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Frequently Asked Questions
What is the freezing point of seawater?
About -1.9 degrees C for typical ocean salinity of 35 ppt, lower than fresh water’s 0 degrees.
How does salinity affect freezing point?
More dissolved salt lowers the freezing point, roughly 0.054 degrees C per part per thousand of salinity.
Why does the ocean not freeze easily?
Its salt content depresses the freezing point and its huge heat capacity resists temperature change.