Celsius ↔ Kelvin Converter

Convert between Celsius and Kelvin instantly

Enter Celsius value to convert to Kelvin
Enter Kelvin value to convert to Celsius
Conversion Result
25°C = 298.15K
25°C = 298.15K • 77°F • Room Temperature

📚 Celsius ↔ Kelvin Conversion Details

Celsius to Kelvin Formula

K = °C + 273.15

To convert Celsius to Kelvin, add 273.15 to the Celsius value.

Example: 25°C = 25 + 273.15 = 298.15K

Kelvin to Celsius Formula

°C = K - 273.15

To convert Kelvin to Celsius, subtract 273.15 from the Kelvin value.

Example: 300K = 300 - 273.15 = 26.85°C

Bidirectional Conversion

This converter works both ways simultaneously:

  • Type in Celsius → Kelvin updates automatically
  • Type in Kelvin → Celsius updates automatically
  • No buttons to click - works as you type

Temperature Scales

  • Celsius (°C): Metric system temperature scale
  • Kelvin (K): Absolute temperature scale
  • Relation: 0K = -273.15°C
  • Increment: 1°C = 1K difference

🌡️ How This Converter Works

This is a bidirectional converter that works in real-time:

  1. Celsius → Kelvin: When you type in the Celsius field, the Kelvin field automatically updates
  2. Kelvin → Celsius: When you type in the Kelvin field, the Celsius field automatically updates
  3. No swapping needed: Both conversions happen simultaneously
  4. Real-time: Updates happen as you type, no button clicks required
// Bidirectional Conversion Logic:
K = °C + 273.15
°C = K - 273.15

// Example 1: Type "25" in Celsius
K = 25 + 273.15 = 298.15

// Example 2: Type "373.15" in Kelvin
°C = 373.15 - 273.15 = 100

📊 Conversion Table

Celsius (°C) Kelvin (K) Description
-273.15°C 0K Absolute Zero
0°C 273.15K Water Freezes
20°C 293.15K Room Temperature
37°C 310.15K Human Body
100°C 373.15K Water Boils
500°C 773.15K Oven Temperature

🎓 Key Facts About Celsius and Kelvin

Celsius Scale

• Invented by Anders Celsius in 1742
• Originally called "centigrade"
• Based on water's freezing (0°C) and boiling (100°C) points
• Used worldwide (except in the USA for everyday use)
• Part of the metric system (SI)

Kelvin Scale

• Named after Lord Kelvin (William Thomson)
• Absolute temperature scale (0K = absolute zero)
• No negative values exist
• Official SI unit for temperature
• Used in scientific and engineering applications
• 1K increment equals 1°C increment

❓ Frequently Asked Questions

Q: What's the difference between Celsius and Kelvin?

A: Celsius is a relative scale based on water's freezing/boiling points, while Kelvin is an absolute scale where 0K represents absolute zero (-273.15°C). The size of 1 degree is the same in both scales.

Q: Why do we add 273.15 instead of just 273?

A: 273.15 is the exact conversion factor. 0°C equals 273.15K exactly. Using 273 would give a slight error of 0.15 degrees.

Q: Can temperature be negative in Kelvin?

A: No, Kelvin is an absolute temperature scale. 0K is absolute zero, the lowest possible temperature where molecular motion stops. Negative Kelvin temperatures don't exist in conventional systems.

Q: Which is better for scientific work: Celsius or Kelvin?

A: Kelvin is preferred for scientific work because it's an absolute scale. However, Celsius is often used in everyday scientific reporting because it's more intuitive for most people.