Boiling Points Across Temperature Scales: °C, °F, K & °R
Water’s boiling point on the four scales
At standard sea-level pressure, pure water boils at:
- 100°C (Celsius)
- 212°F (Fahrenheit)
- 373.15 K (Kelvin)
- 671.67 °R (Rankine)
Why those particular numbers?
The Celsius scale was literally built around this event: 0 for freezing, 100 for boiling, a clean century between the two anchor points. Fahrenheit arrives at 212 by historical accident, which puts exactly 180 Fahrenheit degrees between freezing (32°F) and boiling - half a circle, which some historians suspect was no accident at all.
Kelvin and Rankine simply shift their sibling scales down to absolute zero: K = °C + 273.15, and °R = °F + 459.67. Translate any reading yourself with the Celsius to Fahrenheit and Celsius to Kelvin converters.
Boiling points of common substances across scales
Every liquid has its own boiling point, and lining them up across scales shows just how wide the range is - from helium boiling a few degrees above absolute zero to tungsten holding out past 5,500°C.
| Substance | Celsius | Fahrenheit | Kelvin | Rankine | Notes |
|---|---|---|---|---|---|
| Liquid helium | -268.93°C | -452.07°F | 4.22 K | 7.6 °R | Coldest boiling point of any element |
| Liquid nitrogen | -195.79°C | -320.42°F | 77.36 K | 139.25 °R | Boils on contact with room air |
| Ethanol | 78.37°C | 173.07°F | 351.52 K | 632.74 °R | Boils before water, which is why stills work |
| Water | 100°C | 212°F | 373.15 K | 671.67 °R | At sea-level pressure |
| Mercury | 356.73°C | 674.11°F | 629.88 K | 1,133.78 °R | Ceiling for old mercury thermometers |
| Table salt | 1,465°C | 2,669°F | 1,738.15 K | 3,128.67 °R | Molten salt boils white-hot |
| Iron | 2,862°C | 5,183.6°F | 3,135.15 K | 5,643.27 °R | |
| Tungsten | 5,555°C | 10,031°F | 5,828.15 K | 10,490.67 °R | Highest boiling point of any element |
Why boiling points move with pressure
A liquid boils when its vapor pressure matches the pressure pushing down on it, so less air pressure means an earlier boil. In Denver at 5,280 ft, water boils near 203°F (95°C); on Everest it boils around 160°F (71°C), too cool to brew proper tea. A pressure cooker runs the trick in reverse, raising the boiling point to about 250°F (121°C) to cook food faster.
The full altitude table, plus cooking adjustments, lives in our guide to the boiling point of water. For the other end of the kettle, see freezing points in different temperature scales.
Boiling points beyond Earth
Boiling depends on pressure, so the same water boils at wildly different temperatures across the solar system:
- Mount Everest (8,849 m): about 160°F (71°C) - tea brewed at the summit is famously weak.
- Commercial aircraft cabins (pressurized to ~8,000 ft): water boils near 197°F (92°C), one reason airline coffee struggles.
- Mars: the atmosphere is so thin that water boils at roughly 50°F (10°C) - liquid water and warm days cannot coexist there.
- Hard vacuum: water boils at any temperature, then the evaporation chills the remainder until it freezes - boiling and freezing at once.
The pressure side of this story lives in our barometric pressure guide.