Temperature Converter
Convert Celsius, Fahrenheit, and Kelvin with absolute-zero validation.
- Free
- No signup
- Runs in your browser
Enter a value to see the conversion.
How it works
How to use
Enter a physical temperature and choose Celsius, Fahrenheit, or Kelvin.
Method
Temperature uses offset-aware formulas. Values below absolute zero are rejected.
Example
0 °C equals 32 °F and 273.15 K.
From Celsius
For Fahrenheit, multiply the Celsius reading by 9/5 and then add 32: °F = °C × 9/5 + 32. For Kelvin, keep the same interval size and shift the zero point by 273.15: K = °C + 273.15.
Example: 25 °C becomes 77 °F and 298.15 K.
From Fahrenheit
Remove Fahrenheit's 32-degree offset first, then rescale the interval: °C = (°F − 32) × 5/9. To reach Kelvin, use that Celsius result and add 273.15.
Example: 68 °F → (68 − 32) × 5/9 = 20 °C → 293.15 K.
From Kelvin
Kelvin and Celsius use equal-sized intervals, so Celsius is simply °C = K − 273.15. Fahrenheit follows by applying the Celsius-to-Fahrenheit formula to that result: °F = (K − 273.15) × 9/5 + 32.
Example: 373.15 K becomes 100 °C and 212 °F.
Absolute zero sets the floor
SnakTool rejects a temperature below 0 K, which is −273.15 °C or −459.67 °F. Negative Celsius and Fahrenheit values are valid when they remain above that physical boundary. Values extremely close to absolute zero are normalized to the boundary by the converter's numerical tolerance.
Temperature readings are not temperature differences
The offsets above belong to scale readings. They do not belong to changes in temperature. A rise of 10 °C is a rise of 10 K and 18 °F, even though a reading of 10 °C converts to 50 °F.
Kelvin is written K without a degree sign. Celsius and Fahrenheit use °C and °F.
Frequently asked questions about Temperature Converter
Why does temperature need formulas instead of one conversion factor?
Celsius, Fahrenheit, and Kelvin do not all share the same zero point, and Fahrenheit also uses a different interval size. Converting a reading therefore requires an offset as well as scaling.
Where do Celsius and Fahrenheit show the same number?
At −40: −40 °C equals −40 °F.
What is the Celsius to Fahrenheit formula?
Use °F = °C × 9/5 + 32.
What is the Fahrenheit to Celsius formula?
Use °C = (°F − 32) × 5/9.
How do I convert Celsius to Kelvin?
Add 273.15 to the Celsius reading.
How do I convert Kelvin to Celsius?
Subtract 273.15 from the Kelvin reading.
What is absolute zero in Celsius and Fahrenheit?
Absolute zero is −273.15 °C, which is −459.67 °F and 0 K.
Can Celsius and Fahrenheit temperatures be negative?
Yes. Negative readings are valid on both scales as long as the temperature is not below absolute zero.
Does Kelvin use a degree symbol?
No. Kelvin is written with K, such as 300 K, not °K.