Temperature Converter
Convert between Celsius, Fahrenheit and Kelvin instantly, with the correct formulas.
Convert temperature between °C, °F and K
The Temperature Converter instantly converts between the three temperature scales people use every day and in science — Celsius, Fahrenheit, and Kelvin. Enter a value, choose your scales, and the precise result appears immediately. Unlike length or weight, temperature scales do not share a simple multiplier, so this tool applies the correct formulas for you, including the offsets that trip people up.
The three temperature scales
Celsius (°C) sets water's freezing point at 0 and boiling at 100, and is used by most of the world. Fahrenheit (°F) places freezing at 32 and boiling at 212, and is standard in the United States. Kelvin (K) is the scientific scale that starts at absolute zero, the coldest possible temperature; it shares the same step size as Celsius but is offset by 273.15.
The conversion formulas
| Conversion | Formula |
|---|---|
| Celsius → Fahrenheit | (°C × 9/5) + 32 |
| Fahrenheit → Celsius | (°F − 32) × 5/9 |
| Celsius → Kelvin | °C + 273.15 |
| Kelvin → Celsius | K − 273.15 |
Handy reference points
- Water freezes at 0°C = 32°F = 273.15K.
- Water boils at 100°C = 212°F = 373.15K.
- Normal body temperature is about 37°C = 98.6°F.
- A comfortable room is around 21°C = 70°F.
- −40° is the same in both Celsius and Fahrenheit.
How to use it
- Type a temperature into the From field.
- Select the scale you are converting from and the scale you want.
- Read the result instantly, or swap to reverse the direction.
Why temperature conversion is different
Most unit conversions are a single multiplication, but temperature scales have different zero points, so you must both scale and shift. That is why 0°C is 32°F, not 0°F. Forgetting the offset is the most common mistake in manual conversion. This tool bakes the offsets into its formulas so the result is always correct, whether you are checking a weather forecast, following a recipe, or doing science homework.
Private and free
Every conversion runs locally in your browser with no uploads and no limits. Use it as often as you like, completely free.
Frequently asked questions
How do I convert Celsius to Fahrenheit?
Multiply by 9/5 and add 32. For example, 20°C × 9/5 + 32 = 68°F.
How do I convert Fahrenheit to Celsius?
Subtract 32, then multiply by 5/9. For example, (98.6 − 32) × 5/9 = 37°C.
What is Kelvin?
Kelvin is the scientific temperature scale starting at absolute zero. Add 273.15 to a Celsius value to get Kelvin.
At what temperature are Celsius and Fahrenheit equal?
At −40 degrees: −40°C equals −40°F.