Unit Converter

Convert From Celsius and Kelvin and Vice Versa

Celsius ↔ Kelvin

Type in either Celsius or Kelvin — it’ll convert to the other automatically!


↔

🌡️ What is Celsius (°C)?

Celsius is a metric unit of temperature where water freezes at 0°C and boils at 100°C. It’s widely used in daily life, science, and education across the globe.

❄️ What is Kelvin (K)?

Kelvin is the base unit of temperature in the International System of Units (SI). It starts from **absolute zero**—the lowest possible temperature, where particles stop moving—defined as 0 K. Water freezes at 273.15 K and boils at 373.15 K.

🧠 Quick Comparison

Scale Freezing Point Boiling Point Used In
Celsius (°C) 0°C 100°C Everyday, global use
Kelvin (K) 273.15 K 373.15 K Science, physics, thermodynamics

🧮 How to Convert

Celsius to Kelvin: K = °C + 273.15
Kelvin to Celsius: °C = K − 273.15

Example:
25°C + 273.15 = 298.15 K

🧪 Real-World Temperature Examples (in Kelvin)

  • 0 K – Absolute zero (no molecular motion)
  • 77 K – Liquid nitrogen
  • 273.15 K – Water freezing point
  • 310.15 K – Average human body temperature
  • 373.15 K – Water boiling point
  • 5778 K – Surface of the Sun 🌞

🧠 Nerdy Science Facts

  • Absolute zero (0 K) is the lowest possible temperature—particles stop moving completely.
  • The cold vacuum of outer space is around 2.7 K—just above absolute zero!
  • Kelvin doesn’t use the “degree” symbol because it’s an absolute scale, not relative like Celsius or Fahrenheit.

📜 Timeline: History of the Kelvin Scale

  • 1848: Lord Kelvin proposes the absolute temperature scale.
  • 1954: Kelvin becomes an official SI unit of temperature.
  • 2019: Kelvin is redefined using the Boltzmann constant for improved scientific accuracy.

💡 Kelvin vs Celsius vs Fahrenheit

Temperature Kelvin (K) Celsius (°C) Fahrenheit (°F)
Absolute Zero 0 K -273.15°C -459.67°F
Freezing Point of Water 273.15 K 0°C 32°F
Human Body Temperature 310.15 K 37°C 98.6°F
Boiling Point of Water 373.15 K 100°C 212°F
Surface of the Sun 5778 K 5504.85°C 9940.7°F

💡 Pro Tip

Kelvin is absolute—there are no negative Kelvin values. It’s ideal for use in physics, astronomy, and cryogenics.

🎉 Did You Know?

The Kelvin scale was named after Lord Kelvin (William Thomson), who developed the concept of absolute zero.

🔬 Common Use Cases

  • 🧪 Scientific temperature measurement
  • 🌌 Space and astrophysics
  • 🌡️ Thermodynamic equations
  • ❄️ Cryogenic research