Temperature Converter | Convert Celsius, Fahrenheit, Kelvin

📖 How to Use This Temperature Converter

Enter the temperature value - Type the number you want to convert.

Select the source unit - Choose Celsius, Fahrenheit, or Kelvin.

Select the target unit - Choose the unit you want to convert to.

Get instant results - The converted value appears automatically as you type or change units.

🌡️ Understanding Temperature Scales

Temperature is a measure of the average kinetic energy of particles in a substance. Three main temperature scales are used worldwide:

Celsius (°C): Also known as centigrade, used in most countries for daily temperature, weather, and scientific work. 0°C = freezing point of water, 100°C = boiling point of water at sea level.
Fahrenheit (°F): Used primarily in the United States. 32°F = freezing point of water, 212°F = boiling point of water at sea level.
Kelvin (K): The scientific absolute temperature scale used in physics and chemistry. 0 K = absolute zero (lowest possible temperature), no degree symbol used. Water freezes at 273.15 K, boils at 373.15 K.

📊 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

💡 Common Temperature Reference Points

Absolute Zero: -273.15°C = -459.67°F = 0 K
Freezing point of water: 0°C = 32°F = 273.15 K
Human body temperature: 37°C = 98.6°F = 310.15 K
Room temperature: 20-22°C = 68-72°F = 293-295 K
Boiling point of water: 100°C = 212°F = 373.15 K
Typical summer day: 30°C = 86°F = 303.15 K
Typical winter day: 0°F = -17.8°C = 255.37 K

🌍 Which Countries Use Celsius vs Fahrenheit?

Celsius: Used by almost all countries worldwide (metric system)
Fahrenheit: Used primarily in the United States, its territories, and a few other countries (Bahamas, Cayman Islands, Liberia)
Kelvin: Used in scientific research and engineering globally

❓ Frequently Asked Questions (FAQ)

How do I convert Celsius to Fahrenheit quickly?

Multiply °C by 9, divide by 5, then add 32. For quick mental approximation: multiply °C by 2 and add 30 (e.g., 20°C × 2 = 40 + 30 = 70°F, actual 68°F).

Why does the US use Fahrenheit instead of Celsius?

Historical reasons - Fahrenheit was well-established before the metric system became popular. The US has not officially adopted the metric system for daily temperature measurement, though science and medicine use Celsius.

What is absolute zero and why can't we reach it?

Absolute zero (0 K, -273.15°C) is the theoretical point where particles have minimum thermal motion. Quantum mechanics prevents reaching absolute zero because particles have zero-point energy, though we can get extremely close (nanokelvin range).

Why doesn't Kelvin use a degree symbol?

Kelvin is an "absolute" scale based on thermodynamics, not a "degree" scale. It uses the same increment as Celsius but starts at absolute zero. The correct notation is "K" not "°K".

At what temperature are Celsius and Fahrenheit equal?

Celsius and Fahrenheit are equal at -40 degrees (-40°C = -40°F). This is the only temperature where both scales match.

Can I convert negative temperatures?

Yes! Negative temperatures work perfectly for Celsius and Fahrenheit. Kelvin cannot be negative (0 K is absolute zero).