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 · triple-point temperature
Also 32.02 °F
Triple-point temperature · specified
A little perspective
Water triple point vs Gallium melting plateau at standard pressure: temperature comparison
The water triple point is 29.75 K lower than the equilibrium melting temperature near 101 kPa of the melting plateau of gallium at standard pressure.
The water triple point is the unique temperature and pressure at which water can exist simultaneously as solid, liquid, and vapour in equilibrium.
This is the temperature at which pure gallium changes from solid to liquid under normal atmospheric pressure.
Measurements, assumptions & sources +
Water triple point
Triple-point temperature: 0.01 °C; specified.
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
Equilibrium melting temperature near 101 kPa: 29.76 °C; specified; range 29.75 °C–29.77 °C.
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.
Use the visual comparison to explore its scale, then check the measurements and sources.
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Why this measurement?
Why we use 0.01 °C
We compare the water triple point. This value follows a stated specification; check its scope in the notes.
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 picture identifies the subject; the diagram compares the recorded values. How calibrated comparisons work →
Recorded properties
Dimensions and measurements
| Property | Selected value | Recorded range | Basis |
|---|---|---|---|
| 0.01 °C | Not recorded | specified |
Around this scale
Explore nearby values.
Compare examples with lower, similar and higher values. Each card names the measurement being compared.
Nearest lower valueTemperatureFreezing water0 °CTemperatureFreezing water is liquid water at the temperature where it begins to turn into ice under normal pressure.Around the same scaleTemperatureA freezing winter day-10 °CTemperatureA freezing winter day is weather cold enough for outdoor water to turn to ice.Nearest higher valueTemperatureFood refrigerator interior4 °CDefined interior temperatureFood 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.