Temperature Converter

Convert between Celsius, Fahrenheit and Kelvin instantly

What is it and how does it work?

A temperature converter changes a temperature between the three scales people use: Celsius, Fahrenheit and Kelvin. Most of the world measures everyday temperature in Celsius, the United States uses Fahrenheit, and science uses Kelvin, so converting between them comes up constantly — following a recipe in another country's units, reading a weather report, or doing a physics calculation. Each scale measures the same physical thing but starts and steps differently, which is exactly why a quick mental conversion so often goes wrong.

The relationships are fixed but not obvious: Celsius and Fahrenheit have different zero points and different sized degrees, so you cannot just add or multiply by a round number — water freezes at 0°C but 32°F. Kelvin shares the size of a Celsius degree but starts at absolute zero, the coldest possible temperature, so it is Celsius shifted by 273.15. A converter applies the correct formula for whichever direction you need, instantly, so you get an accurate result instead of a rough guess. This tool runs in your browser as you type.

Common use cases

• Following a recipe: convert an oven temperature from Fahrenheit to Celsius or back to match your appliance.
• Reading a foreign forecast: turn a weather temperature into the scale you are used to.
• Doing science: convert a Celsius reading to Kelvin for a physics or chemistry calculation.

Frequently asked questions

How do I convert Celsius to Fahrenheit?

Multiply the Celsius value by 9/5 and add 32. So 20°C is (20 × 9/5) + 32 = 68°F. The reverse subtracts 32 first, then multiplies by 5/9. The two scales have different zero points and degree sizes, which is why the formula is not a simple multiplication.

What is Kelvin and why is it used in science?

Kelvin starts at absolute zero — the coldest temperature physically possible — and uses the same degree size as Celsius, so K = °C + 273.15. Because it has no negative values and a true zero, it suits physics and chemistry where temperature ratios and gas laws need an absolute scale.

Why can't I just convert in my head with a round number?

Because Celsius and Fahrenheit differ in both their zero point and their degree size, the conversion involves a multiplication and an addition, not a single round factor. Approximations get you close but drift off for precise needs like cooking or science, where the exact formula matters.

What is absolute zero?

Absolute zero is the lowest possible temperature, where particles have minimal motion — 0 Kelvin, equal to about −273.15°C or −459.67°F. It is the starting point of the Kelvin scale, which is why Kelvin has no negative values: nothing can be colder than absolute zero.

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