Temperature Converter
Convert between Celsius, Fahrenheit and Kelvin with correct formulas and an absolute-zero sanity check — free and private.
Recipes, weather reports and science homework all use different temperature scales, and this converter bridges them instantly. It applies the exact formulas rather than rough rules of thumb, and it refuses impossible values below absolute zero. Type a temperature and the converted result updates live in the scale you need.
Uses the exact formulas; values below −273.15 °C are rejected.
How to use the Temperature Converter
- Type the temperature you want to convert in the box.
- Select the starting scale in the From list and the target scale in the To list.
- The converted temperature appears instantly — values below absolute zero are flagged as invalid.
Temperature Converter — FAQs
What formulas does this converter use?
It uses the exact definitions: Fahrenheit equals Celsius times 9/5 plus 32, and Kelvin equals Celsius plus 273.15. Conversions go through Celsius as the intermediate step with full floating-point precision, so 98.6 °F becomes exactly 37 °C, not an approximation.
Why was my value rejected as invalid?
Nothing can be colder than absolute zero, which is −273.15 °C, −459.67 °F or 0 K. If the tool flags your input, the value is physically impossible, which usually means a typo or the wrong scale was selected. Fix the input and the conversion will proceed normally.
When should I use Kelvin instead of Celsius?
Kelvin is the scientific scale for physics, chemistry and engineering because it starts at absolute zero, making ratios and gas laws work correctly. Everyday life, weather and cooking use Celsius or Fahrenheit, while lab calculations and thermodynamics problems generally expect Kelvin.
Is my data uploaded anywhere?
Your data never leaves your device. This converter runs entirely in your browser using JavaScript, so nothing is uploaded, stored, shared or tracked. It works offline too, and you can use it as often as you like with complete confidence.