🌡️ Temperature Converter
Convert temperatures between Celsius, Fahrenheit, and Kelvin instantly
📏 Temperature Input
📊 Conversion Results
Converted Temperature
Celsius (°C)
Fahrenheit (°F)
Kelvin (K)
📚 Understanding Temperature Scales
What is Temperature?
Temperature is a measure of the average kinetic energy of particles in a substance. Different temperature scales have been developed throughout history, each with its own reference points and applications.
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
About Temperature Scales
- Celsius (°C): Most commonly used worldwide. Water freezes at 0°C and boils at 100°C at standard atmospheric pressure. Named after Swedish astronomer Anders Celsius.
- Fahrenheit (°F): Primarily used in the United States. Water freezes at 32°F and boils at 212°F. Named after German physicist Daniel Gabriel Fahrenheit.
- Kelvin (K): SI unit for thermodynamic temperature. Starts at absolute zero (0 K), the coldest possible temperature. No degree symbol is used with Kelvin. Named after Lord Kelvin.
Common Temperature Reference Points
- Absolute Zero: -273.15°C = -459.67°F = 0 K (coldest possible temperature)
- Water Freezing Point: 0°C = 32°F = 273.15 K
- Room Temperature: ~20-22°C = 68-72°F = 293-295 K
- Human Body Temperature: 37°C = 98.6°F = 310.15 K
- Water Boiling Point: 100°C = 212°F = 373.15 K (at sea level)
- Surface of the Sun: ~5,500°C = ~9,932°F = ~5,773 K
When to Use Each Scale
- Celsius: Everyday use in most countries, weather forecasts, cooking, medical applications
- Fahrenheit: Everyday use in the United States, some Caribbean countries
- Kelvin: Scientific research, physics, chemistry, astronomy, engineering calculations
Interesting Temperature Facts
- The Fahrenheit scale was originally based on three reference points: 0°F (coldest temperature achievable with ice and salt), 32°F (water freezing), and 96°F (human body temperature)
- Kelvin is the only temperature scale that doesn't use degrees - we say "300 Kelvin" not "300 degrees Kelvin"
- At -40 degrees, Celsius and Fahrenheit scales intersect (-40°C = -40°F)
- Absolute zero (0 K) has never been achieved, though scientists have gotten extremely close
- The hottest temperature ever recorded on Earth was 56.7°C (134°F) in Death Valley, California
- The coldest temperature ever recorded on Earth was -89.2°C (-128.6°F) in Antarctica
Frequently Asked Questions
Why are there different temperature scales?
Different temperature scales were developed at different times and places for different purposes. Fahrenheit was created for practical everyday use, Celsius was designed around the properties of water, and Kelvin was developed for scientific applications based on absolute zero.
Which temperature scale is most accurate?
All temperature scales are equally accurate - they're just different ways of measuring the same thing. Kelvin is preferred in science because it starts at absolute zero and has no negative numbers, making calculations simpler.
Why doesn't Kelvin use degrees?
Kelvin is an absolute temperature scale starting at absolute zero, not a relative scale like Celsius or Fahrenheit. The SI convention is to refer to it simply as "kelvin" without the degree symbol, treating it as a base unit like meters or kilograms.
At what temperature are Celsius and Fahrenheit equal?
Celsius and Fahrenheit are equal at -40 degrees (-40°C = -40°F). This is the only point where the two scales intersect. You can verify this using the conversion formula: (-40 × 9/5) + 32 = -40.
Can temperature go below absolute zero?
No, absolute zero (0 K or -273.15°C) is the lowest possible temperature. At this point, particles have minimal kinetic energy. While scientists have created systems with "negative absolute temperatures" in quantum physics, these are actually hotter than any positive temperature.
Why does the US use Fahrenheit instead of Celsius?
The US adopted Fahrenheit before the metric system became widespread. While there have been attempts to switch to Celsius, the change never fully took hold due to the cost of conversion and public resistance to changing familiar measurements. The US remains one of the few countries still using Fahrenheit for everyday temperatures.
How do I quickly estimate Celsius to Fahrenheit?
A quick approximation: double the Celsius temperature and add 30. For example, 20°C ≈ (20 × 2) + 30 = 70°F (actual: 68°F). For Fahrenheit to Celsius: subtract 30 and divide by 2. This gives you a rough estimate within a few degrees.