Temperature Converter
What Are Temperature Scales?
Temperature is a measure of how hot or cold something is, and different scales have been developed to quantify it. Celsius (°C), created by Anders Celsius in 1742, is used worldwide for everyday purposes and is based on water's freezing (0°C) and boiling (100°C) points. Fahrenheit (°F), developed by Daniel Fahrenheit in 1724, is primarily used in the United States. Kelvin (K), the SI unit for scientific measurement, starts at absolute zero — the lowest theoretically possible temperature where all molecular motion stops (0 K = −273.15°C).
How to Use
Enter a temperature value and select the input unit. All three conversions (Celsius, Fahrenheit, and Kelvin) are displayed instantly as you type.
Temperature Scales
Celsius: water freezes at 0° and boils at 100°. Fahrenheit: water freezes at 32° and boils at 212°. Kelvin: absolute zero is 0K (−273.15°C). The formulas are: °F = °C × 9/5 + 32, K = °C + 273.15.
Common Use Cases
- Cooking — convert recipe temperatures between Celsius and Fahrenheit
- Travel — understand weather forecasts in unfamiliar temperature scales
- Science — convert between Celsius and Kelvin for lab work
- Healthcare — convert body temperature readings between scales
- HVAC and engineering — work with specifications in different unit systems
Quick Reference
Some handy reference points: body temperature is approximately 37°C / 98.6°F / 310 K. Room temperature is about 20-22°C / 68-72°F. Water boils at 100°C / 212°F / 373 K at sea level. A comfortable swimming pool is around 26-28°C / 79-82°F. The intersection point where Celsius and Fahrenheit read the same is −40°.
Privacy
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FAQ
What is the difference between Celsius, Fahrenheit, and Kelvin?
Celsius is the everyday scale with water freezing at 0° and boiling at 100°. Fahrenheit, used mainly in the US, sets those points at 32° and 212°. Kelvin is the SI unit for science, starting at absolute zero (−273.15°C), with the same degree size as Celsius.
What is the formula to convert Celsius to Fahrenheit?
°F = °C × 9/5 + 32. To go the other way, °C = (°F − 32) × 5/9. Kelvin converts with K = °C + 273.15.
Is the value I enter sent to a server?
No. All conversions run in your browser with JavaScript, and the temperatures you enter are never sent to or stored on any server.
Can I enter a temperature below absolute zero?
The tool will still compute conversions for negative Kelvin values, but nothing can physically be colder than −273.15°C (0 K). Check that the Kelvin result is not negative to catch input mistakes.
Is there a temperature where Celsius and Fahrenheit are equal?
Yes, −40°. −40°C and −40°F are exactly the same temperature — the only point where the two scales intersect.