Convert Triple Point of Water to Rankine
Convert triple points of water to degrees rankine instantly. 1 TPW = 491.688 °R — use the live calculator, the exact formula, a reference-temperature table and worked examples. Also check the Rankine to Triple Point of Water converter for the reverse conversion.
Units explained
Triple Point of Water
The triple point of water is the unique state at which ice, liquid water, and water vapor coexist in equilibrium — exactly 273.16 K (0.01 °C). Treated as a converter unit, 1 triple point of water equals exactly 273.16 kelvins.
Adopted as thermometry's master fixed point because it is exactly reproducible in a sealed glass cell, unlike freezing and boiling points, which shift with atmospheric pressure and dissolved impurities.
Calibration laboratories and the International Temperature Scale of 1990 (ITS-90); from 1954 to 2019 the kelvin itself was defined as exactly 1/273.16 of this temperature.
Fixed at exactly 273.16 K by the 10th CGPM in 1954; it remained the kelvin's defining point until the 2019 SI redefinition through the Boltzmann constant.
Rankine
The degree Rankine (°R) is the absolute counterpart of the Fahrenheit scale: 0 °R is absolute zero, and one degree Rankine is exactly the same size as one degree Fahrenheit (5/9 of a kelvin). Water freezes at 491.67 °R.
Named for William John Macquorn Rankine, the Scottish engineer and physicist who proposed an absolute scale built from Fahrenheit-sized degrees, paralleling Kelvin's absolute scale built from Celsius-sized degrees.
Used mainly in United States aerospace, thermodynamics, and power-plant engineering, where calculations demand absolute temperature but legacy data, instruments, and codes are in Fahrenheit.
Proposed by W. J. M. Rankine at the University of Glasgow in 1859, eleven years after Lord Kelvin's absolute scale of 1848.
Triple Point of Water to Rankine conversion formula
The exact relationship between triple points of water and degrees rankine:
To convert triple points of water to degrees rankine, multiply the value in triple points of water by 491.688. To reverse, multiply the value in degrees rankine by 0.002033810058.
Both units count upward from absolute zero, so 0 TPW = 0 °R and the relationship is a pure ratio.
How to use this converter
Type a value into the calculator. The result in degrees rankine updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Rankine to Triple Point of Water converter for the reverse direction.
Step-by-step: convert triple points of water to degrees rankine
- Write down the temperature in triple points of water (TPW).
- Multiply the value in triple points of water by 491.688.
- The result is the same temperature expressed in degrees rankine (°R).
- To reverse, multiply the value in degrees rankine by 0.002033810058 — or open the Rankine to Triple Point of Water converter.
Worked examples
Example 1 — Convert 1 TPW to °R:
1 × 491.688 = 491.688 °R
Example 2 — Convert 100 TPW to °R:
100 × 491.688 = 49168.8 °R
Triple Point of Water to Rankine conversion table
Physically meaningful reference temperatures, from absolute zero to the surface of the Sun, converted from triple points of water to degrees rankine:
| Triple Point of Water [TPW] | Rankine [°R] | Reference point |
|---|---|---|
| 0 | 0 | Absolute zero |
| 0.8535290672 | 419.67 | Where Celsius and Fahrenheit coincide (−40°) |
| 0.9348814695 | 459.67 | Zero Fahrenheit (0 °F) |
| 0.9999633914 | 491.67 | Water freezes (0 °C / 32 °F) |
| 1 | 491.688 | Triple point of water |
| 1.0365719725 | 509.67 | Cool day (10 °C / 50 °F) |
| 1.0731805535 | 527.67 | Room temperature (20 °C / 68 °F) |
| 1.091484844 | 536.67 | Standard laboratory temperature (25 °C) |
| 1.1097891346 | 545.67 | Hot day (30 °C / 86 °F) |
| 1.1354151413 | 558.27 | Human body temperature (37 °C / 98.6 °F) |
| 1.1463977156 | 563.67 | Heat-wave day (40 °C / 104 °F) |
| 1.1830062967 | 581.67 | Hot tap water (50 °C / 122 °F) |
| 1.3660492019 | 671.67 | Water boils (100 °C / 212 °F) |
| 1.6589178503 | 815.67 | Moderate baking oven (180 °C / 356 °F) |
| 21.1524381315 | 10400.4 | Surface of the Sun (≈5,505 °C) |
Frequently asked questions
How many degrees rankine is 1 triple point of water?
How do I convert triple points of water to degrees rankine?
How do I convert degrees rankine back to triple points of water?
How many degrees rankine is 100 triple points of water?
Can a temperature be below absolute zero?
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Modern Standard Scales (4 units)
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Scientific & Fixed-Point (2 units)
Sources & references
Conversion relationship (1 TPW = 491.688 °R) verified against the following authoritative sources:
- BIPM — The International System of Units (SI Brochure 9th ed.)
Official BIPM publication defining the seven SI base units (including the meter) and the rules for their use. The global authority on units of measurement.
- NIST — Guide to the SI
US National Institute of Standards and Technology reference covering the SI base and derived units with definitions and usage rules for US technical practice.
- NIST Special Publication 811 — Guide for the Use of the International System of Units
Detailed NIST guide covering exact conversion factors between SI and US customary units along with formatting and rounding conventions.
- BIPM — International Temperature Scale of 1990 (ITS-90)
The internationally agreed practical temperature scale, defining fixed points (including the triple point of water at 273.16 K) and interpolation instruments used by national metrology institutes for thermometer calibration worldwide.
- CODATA Internationally Recommended Values of the Fundamental Physical Constants
Committee on Data of the International Science Council; authoritative source for the masses of fundamental particles (electron, proton, neutron) and the atomic mass constant.