Three Scales, Three Histories
- Celsius (°C): The metric standard. 0°C = water freezes, 100°C = water boils (at sea level). Used worldwide for weather, cooking, and most scientific contexts outside physics.
- Fahrenheit (°F): Still dominant in the US for weather and cooking. 32°F = water freezes, 212°F = water boils. The scale was designed so 0°F was the freezing point of brine and 100°F was approximate human body temperature.
- Kelvin (K): The SI base unit. 0 K = absolute zero (−273.15°C), the theoretical point where all molecular motion stops. No degree symbol — it's just "K," not "°K." Used in physics, astronomy, and cryogenics. Kelvins are the same size as Celsius degrees.
The Conversion Formulas
°F = (°C × 9/5) + 32
°C = (°F − 32) × 5/9
K = °C + 273.15
°C = K − 273.15To convert Fahrenheit to Kelvin: first convert to Celsius, then add 273.15.
Key Temperature Reference Points
- Absolute zero: −273.15°C / −459.67°F / 0 K — the coldest possible temperature.
- Water freezes: 0°C / 32°F / 273.15 K.
- Room temperature: ~20°C / ~68°F.
- Human body: ~37°C / ~98.6°F (normal; varies by person and time of day).
- Water boils: 100°C / 212°F / 373.15 K (at standard atmospheric pressure; boiling point decreases with altitude).
- Oven temperatures: 180°C / 350°F (moderate), 220°C / 425°F (hot).
Why Converting Matters
- International recipes: A European recipe at 180°C needs 350°F in a US oven.
- Weather apps: Global weather data in Celsius needs Fahrenheit display for US users.
- Scientific data: Converting between Celsius and Kelvin for physics and chemistry calculations.
- Travel: Understanding local weather reports and thermostat settings abroad.
Convert Temperatures Instantly
Use ToolsVito's Temperature Converter to convert between Celsius, Fahrenheit, and Kelvin with live conversion as you type. No mental math, no formula lookup.