Temperature Conversion — Celsius, Fahrenheit & Kelvin

This temperature conversion tool converts between Celsius, Fahrenheit, and Kelvin instantly. Enter any temperature in the converter above and all three values update at once. This page also covers every conversion formula, a full reference chart, and explains when to use each temperature scale.

All Temperature Conversion Formulas

Temperature Conversion Chart

What Is Celsius?

Celsius (°C) is the temperature scale used in everyday life in most countries. It is part of the International System of Units (SI). The scale is defined by two reference points: 0°C for the freezing point of water and 100°C for the boiling point at sea level. The scale was proposed by Swedish astronomer Anders Celsius in 1742.

Celsius is used for weather forecasts, cooking recipes, medical body temperature, and refrigeration standards worldwide. The World Health Organization (WHO) sets fever at 38°C or higher in adults. The global average surface temperature is approximately 15°C (59°F).

What Is Fahrenheit?

Fahrenheit (°F) is the temperature scale used primarily in the United States. On this scale, water freezes at 32°F and boils at 212°F. The 180-degree span between these two points compares to 100 degrees on the Celsius scale. The scale was developed by German physicist Daniel Gabriel Fahrenheit in 1724.

Fahrenheit is used in the US for weather, cooking (oven temperatures), body temperature (98.6°F normal), and industrial applications. Fahrenheit is used by fewer than 5% of countries globally — primarily the United States, Liberia, and Myanmar.

What Is Kelvin?

Kelvin (K) is the SI base unit for thermodynamic temperature. It starts at absolute zero (0 K = −273.15°C), the coldest possible temperature. Kelvin uses the same degree size as Celsius but has no negative values, making it essential for physics and chemistry equations.

According to the International Bureau of Weights and Measures (BIPM), the kelvin has been defined since 2019 by the Boltzmann constant (1.380649 × 10²³ J/K). Scientists use Kelvin for thermodynamic laws, gas calculations, and astrophysics. The surface of the Sun measures approximately 5,778 K (5,505°C).

Quick Conversion Reference

• Body temperature: 37°C = 98.6°F = 310.15 K
• Room temperature: 20°C = 68°F = 293.15 K
• Water boils: 100°C = 212°F = 373.15 K
• Water freezes: 0°C = 32°F = 273.15 K
• Absolute zero: −273.15°C = −459.67°F = 0 K
• Equal point: −40°C = −40°F (the only temperature equal on both scales)

Which Temperature Scale Should You Use?

• Celsius: For weather, cooking, body temperature, and everyday life in most countries.
• Fahrenheit: For recipes or weather in the US, or when communicating with an American audience.
• Kelvin: For physics, chemistry, thermodynamics, astrophysics, and any scientific calculation requiring absolute temperature.

Temperature in Everyday Contexts

Cooking and Baking

Oven temperatures range from about 120°C (250°F) for slow cooking to 260°C (500°F) for high-heat baking. Recipes from US cookbooks use Fahrenheit, while most international recipes use Celsius. A moderate oven is 180°C (356°F). Meat safety temperatures vary by type — poultry must reach at least 74°C (165°F) internally, according to food safety guidelines.

Weather and Climate

The World Meteorological Organization (WMO) reports global temperatures in Celsius. A comfortable outdoor temperature is 18–24°C (64–75°F). Extreme heat is defined as above 40°C (104°F). Extreme cold is below −40°C (−40°F — the point where both scales are equal).

Medicine and Health

Normal human body temperature is 37°C (98.6°F). A fever begins at 38°C (100.4°F). Hypothermia risk begins at a core temperature below 35°C (95°F). Medical refrigerators store vaccines at 2–8°C (36–46°F), as specified by WHO cold chain requirements.

Dedicated Temperature Converters

For step-by-step formulas and extended reference tables, use these dedicated converters:

• Celsius to Fahrenheit converter — full formula, table, and cooking reference
• Fahrenheit to Celsius converter — reverse formula with common weather values
• Celsius to Kelvin converter — absolute zero explained, science reference
• Kelvin to Celsius converter — reverse Kelvin conversion

Limitations of This Converter

• Standard atmosphere assumed: Boiling and freezing points apply at sea level (101.325 kPa). At altitude, water boils below 100°C — at 3,000 m elevation, water boils at approximately 90°C.
• Kelvin floor: Kelvin cannot go below 0 K. Any Celsius value below −273.15°C or Fahrenheit below −459.67°F is physically impossible.
• Rankine not included: The Rankine scale (used in some US engineering applications) is not covered here. To convert: R = °F + 459.67.