Temperature Converter
Convert between Celsius, Fahrenheit, and Kelvin instantly. Free online temperature converter with formulas and reference points.
How do I convert Celsius to Fahrenheit?
Multiply the Celsius temperature by 9/5 (or 1.8) and add 32. Formula: °F = (°C × 9/5) + 32. For example, 25°C = (25 × 9/5) + 32 = 77°F.
How do I convert Fahrenheit to Celsius?
Subtract 32 from the Fahrenheit temperature and multiply by 5/9. Formula: °C = (°F − 32) × 5/9. For example, 77°F = (77 − 32) × 5/9 = 25°C.
How do I convert Celsius to Kelvin?
Add 273.15 to the Celsius temperature. Formula: K = °C + 273.15. For example, 25°C = 298.15 K.
How do I convert Kelvin to Celsius?
Subtract 273.15 from the Kelvin temperature. Formula: °C = K − 273.15. For example, 298.15 K = 25°C.
What is the difference between Celsius, Fahrenheit, and Kelvin?
Celsius (°C) is used worldwide for everyday temperatures. Fahrenheit (°F) is primarily used in the United States. Kelvin (K) is the SI scientific unit, starting at absolute zero with no negative values.
What is absolute zero?
Absolute zero is 0 K (−273.15°C or −459.67°F). It is the lowest possible temperature where all molecular motion theoretically stops.
What are the freezing and boiling points of water?
Water freezes at 0°C (32°F, 273.15 K) and boils at 100°C (212°F, 373.15 K) under standard atmospheric pressure.
What is normal body temperature?
Normal human body temperature is approximately 37°C (98.6°F or 310.15 K), though it can vary slightly among individuals.
Why does the US use Fahrenheit?
The United States inherited the Fahrenheit scale from the British Empire. Most countries switched to Celsius during metrication, but the US has not fully adopted the metric system.
Who invented each temperature scale?
Celsius was proposed by Anders Celsius in 1742. Fahrenheit was created by Daniel Gabriel Fahrenheit in 1724. Kelvin was introduced by Lord Kelvin (William Thomson) in 1848.
At what temperature are Celsius and Fahrenheit equal?
Celsius and Fahrenheit are equal at −40 degrees: −40°C = −40°F.
Is this temperature converter free?
Yes, this tool is completely free, requires no registration, and works directly in your browser.
How to Use Temperature Converter
Convert temperatures between Celsius, Fahrenheit, and Kelvin instantly. Everything runs locally in your browser, so your numbers never leave your device.
- Type a value into the Celsius field — the Fahrenheit and Kelvin boxes update instantly with the converted results.
- Enter a number under Fahrenheit or Kelvin instead, and the other two scales recalculate as you type.
- Open the Formulas section to see the exact equations behind each conversion pair.
- Check the Common Temperatures table for reference points such as the freezing and boiling points of water.
Decimals and negative values are supported, so you can convert sub-zero readings without any extra steps.
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