Temperature Converter
Convert between Celsius (°C), Fahrenheit (°F), and Kelvin (K) with our accurate temperature calculator.
Temperature Conversion
Conversion Result
Conversion History
Understanding Temperature Scales
Celsius (°C)
The Celsius scale sets the freezing point of water at 0°C and the boiling point at 100°C (at standard atmospheric pressure). It's used in most countries worldwide.
Fahrenheit (°F)
The Fahrenheit scale sets the freezing point of water at 32°F and boiling point at 212°F. It's primarily used in the United States and its territories.
Kelvin (K)
The Kelvin scale is the base unit of temperature in the International System of Units (SI). Absolute zero (0K) is the theoretical absence of all thermal energy.
Key Temperatures
Absolute Zero: -273.15°C, -459.67°F, 0K
Freezing Water: 0°C, 32°F, 273.15K
Body Temp: 37°C, 98.6°F, 310.15K
Temperature Conversion Formulas
- Celsius to Fahrenheit: °F = (°C × 9/5) + 32
- Fahrenheit to Celsius: °C = (°F - 32) × 5/9
- Celsius to Kelvin: K = °C + 273.15
- Kelvin to Celsius: °C = K - 273.15
- Fahrenheit to Kelvin: K = (°F - 32) × 5/9 + 273.15
- Kelvin to Fahrenheit: °F = (K - 273.15) × 9/5 + 32
Temperature Questions & Answers
Why does Fahrenheit have such odd numbers for freezing and boiling points?
Daniel Fahrenheit originally defined his scale with 0°F as the temperature of an ice-salt mixture (the coldest temperature he could reliably reproduce) and 96°F as human body temperature. He later adjusted the scale to set water's freezing point at 32°F and boiling point at 212°F, creating 180 degrees between them. This made the scale more precise while keeping the original reference points approximately correct.
What is absolute zero and can we reach it?
Absolute zero (0K or -273.15°C) is the theoretical temperature at which all thermal motion ceases. While scientists have come extremely close (within billionths of a degree), absolute zero cannot actually be reached according to the third law of thermodynamics. The closest achieved temperature is about 0.0000000001K in laboratory conditions.
Why do scientists use Kelvin instead of Celsius?
Kelvin is preferred in scientific work because:
1. It's an absolute scale starting at absolute zero
2. It's the SI base unit for temperature
3. Many physical laws and equations (like the ideal gas law) are simpler when expressed in Kelvin
4. It avoids negative temperatures in thermodynamic calculations
5. Temperature differences are the same in Celsius and Kelvin (1K = 1°C difference)
At what temperature are Celsius and Fahrenheit equal?
Celsius and Fahrenheit scales intersect at -40° (-40°C = -40°F). This is the only temperature where both scales show the same numerical value. You can derive this by setting °F = °C in the conversion formula and solving:
°F = (°C × 9/5) + 32
Let °F = °C = x
x = (x × 9/5) + 32
x - (9/5)x = 32
(-4/5)x = 32
x = -40