Water triple point
The water triple point is the unique temperature and pressure at which water can exist simultaneously as solid, liquid, and vapour in equilibrium.
Also known as: triple point of water
How big is it?
0.01 °C
Also 32.02 °F
Triple-point temperature · specified
A little perspective
Water triple point is 29.75 K cooler than Gallium melting plateau at standard pressure.
Gallium melting plateau at standard pressure: This is the temperature at which pure gallium changes from solid to liquid under normal atmospheric pressure.
Measurements, assumptions & sources +
Water triple point
The triple point of water is 273.16 K for a specified isotopic composition at its equilibrium pressure. It is distinct from ordinary freezing water at atmospheric pressure.
IAPWS — Fundamental physical constants of water
The marked triple-point temperature is calibrated. Unmeasured illustration details are representative.
Gallium melting plateau at standard pressure
Gallium melts at about 302.9146 K (29.7646 °C) near standard pressure. Purity and pressure affect a realised plateau.
The marked equilibrium melting temperature near 101 kpa is calibrated. Unmeasured illustration details are representative.
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Why this measurement?
Why we use 0.01 °C
For comparison, this page uses triple-point temperature. The record labels this value specified, so the stated convention rather than an inferred average controls the comparison.
The triple point of water is 273.16 K for a specified isotopic composition at its equilibrium pressure. It is distinct from ordinary freezing water at atmospheric pressure.
The identifying illustration and the numerical comparison remain separate. How calibrated comparisons work →
Recorded properties
Water triple point dimensions and measurements
| Property | Selected value | Recorded range | Basis |
|---|---|---|---|
| 0.01 °C | Not recorded | specified |
Around this scale
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These links use compatible temperature records, ordered around the selected value.
Nearest lower value · TemperatureFreezing water0 °CFreezing water is liquid water at the temperature where it begins to turn into ice under normal pressure.Around the same scale · TemperatureA freezing winter day-10 °CA freezing winter day is weather cold enough for outdoor water to turn to ice.Nearest higher value · TemperatureFood refrigerator interior4 °CFood refrigerator interior refers to the air temperature inside a fridge, maintained to keep food safe and slow spoilage.Sources and method
Want to check the number?
The source records and measurement method remain available for inspection.
- IAPWS — Fundamental physical constants of waterTriple-point temperature and isotopic-composition convention.
There’s always another scale
Follow your curiosity.
TemperatureFreezing water0 °CFreezing water is liquid water at the temperature where it begins to turn into ice under normal pressure.TemperatureBoiling water100 °CBoiling water is water heated until it changes rapidly from liquid to steam at standard atmospheric pressure.TemperatureGallium melting plateau at standard pressure29.76 °CThis is the temperature at which pure gallium changes from solid to liquid under normal atmospheric pressure.TemperatureA freezing winter day-10 °CA freezing winter day is weather cold enough for outdoor water to turn to ice.TemperatureRoom temperature20 °CRoom temperature describes indoor air conditions generally considered comfortable for people and suitable for ordinary activities.TemperatureA warm summer day30 °CA warm summer day is weather with outdoor air noticeably hotter than average, typical of summer in temperate regions.TemperatureHuman body temperature37 °CHuman body temperature is the internal temperature maintained by a healthy person under normal conditions.TemperatureA 39 °C reading39 °CA fever is a temporary rise in body temperature, commonly associated with the immune system responding to infection or inflammation.