Precision Utility
Temperature
Converter
Scales
3 Scales
Speed
Instant Convert
Convert between Celsius, Fahrenheit and Kelvin in real time. Enter a temperature, choose the source unit, and see all three scales update instantly. Perfect for cooking, travel, science homework or checking the weather.
Enter Temperature
Converted Temperature
68 °F
Celsius
20 °C
Fahrenheit
68 °F
Kelvin
293.15 K
How the temperature converter works
Type any number into the temperature field and choose the unit you're converting from -- Celsius, Fahrenheit or Kelvin. All three results update instantly as you type.
The converter first normalises your input to Celsius, then calculates the other two scales from that base value. This means you always see an accurate, consistent result no matter which direction you convert.
No button press is needed. Every keystroke triggers a fresh calculation, so you can explore different values quickly without waiting.
What you need to know about temperature scales
The three most common temperature scales each have different origins and uses:
- Celsius (°C) -- used by most of the world for weather, cooking and everyday life. Water freezes at 0 °C and boils at 100 °C.
- Fahrenheit (°F) -- used mainly in the United States. Water freezes at 32 °F and boils at 212 °F.
- Kelvin (K) -- the SI unit used in science. It starts at absolute zero (0 K = -273.15 °C). Water freezes at 273.15 K and boils at 373.15 K.
Key conversion formulas:
- °C to °F: multiply by 9/5 then add 32
- °F to °C: subtract 32 then multiply by 5/9
- °C to K: add 273.15
- K to °C: subtract 273.15
Handy reference points:
- Water freezes: 0 °C / 32 °F / 273.15 K
- Water boils: 100 °C / 212 °F / 373.15 K
- Human body temperature: 37 °C / 98.6 °F / 310.15 K
- Absolute zero: -273.15 °C / -459.67 °F / 0 K
- Celsius and Fahrenheit are equal at -40
Frequently asked questions
How do I convert Celsius to Fahrenheit?
Multiply the Celsius value by 9/5 (or 1.8) then add 32. For example, 20 °C = 20 x 1.8 + 32 = 68 °F.
How do I convert Fahrenheit to Celsius?
Subtract 32 from the Fahrenheit value then multiply by 5/9. For example, 68 °F = (68 - 32) x 5/9 = 20 °C.
What is absolute zero?
Absolute zero is the lowest possible temperature -- 0 K, which equals -273.15 °C or -459.67 °F. At this point all molecular motion stops. It has been approached in labs but never fully reached.
Why does the UK use both Celsius and Fahrenheit?
The UK officially adopted Celsius in the 1960s, but Fahrenheit is still widely used in everyday conversation -- especially for warm weather. You'll often hear "80 °F" in summer forecasts alongside the official Celsius reading.
What is the Kelvin scale used for?
Kelvin is the SI base unit of temperature used in science and engineering. It starts at absolute zero and uses the same increment size as Celsius, making it ideal for physics calculations where negative temperatures would be problematic.
At what temperature are Celsius and Fahrenheit the same?
Celsius and Fahrenheit meet at -40. That is, -40 °C = -40 °F. This is the only point where both scales show the same number.