Temperature Converter
Convert between Celsius, Fahrenheit, and Kelvin.
Enter value and units to convert temperature.
What This Converter Does
Celsius, Fahrenheit, and Kelvin all measure the same physical thing on three different scales, none of which line up at a shared zero point, so converting between them isn't as simple as multiplying by a single ratio the way most unit conversions are. This tool handles that directly — enter a temperature, pick the scale it's in and the scale you want, and get an instant, correctly-computed result.
How to Use It
Enter a Value, then choose Celsius, Fahrenheit, or Kelvin for both the From Unit and To Unit. The result displays with the degree symbol and unit letter attached directly to each number (e.g. "0°C is 32°F"), rounded to 2 decimal places — enough precision for virtually any everyday or scientific use without cluttering the result with long decimal strings.
The Formula
Celsius acts as the pivot scale internally, so every conversion passes through it even when neither your source nor target unit is Celsius. Fahrenheit to Celsius is (°F − 32) × 5/9, and Kelvin to Celsius is simply °K − 273.15 (Kelvin and Celsius share the same size of degree, just offset by that constant). Going the other direction, Celsius to Fahrenheit is (°C × 9/5) + 32, and Celsius to Kelvin is °C + 273.15. Converting, say, Fahrenheit directly to Kelvin means the calculator quietly converts Fahrenheit to Celsius first, then Celsius to Kelvin, even though you never see that intermediate number.
A Worked Example
Water boils at 100°C, which converts to (100 × 9/5) + 32 = 180 + 32 = 212°F exactly — a useful anchor point since it's a fixed, well-known reference temperature. Body temperature offers another familiar pair: 37°C converts to (37 × 9/5) + 32 = 66.6 + 32 = 98.6°F, matching the commonly cited "normal" human body temperature in Fahrenheit. Running that same 98.6°F back through the converter to Celsius returns (98.6 − 32) × 5/9 = 66.6 × 5/9 = 37°C exactly, confirming the two formulas are true inverses of each other.
How to Convert Temperature Manually
For Celsius to Fahrenheit: multiply by 9/5 (or 1.8), then add 32 — 100°C × 1.8 = 180, plus 32 = 212°F. For Fahrenheit to Celsius, reverse both steps in the opposite order: subtract 32 first, then multiply by 5/9 — (212 − 32) × 5/9 = 180 × 5/9 = 100°C. Kelvin is the easiest of the three: it's identical in size to Celsius, just shifted by exactly 273.15, so add that to go from Celsius to Kelvin, or subtract it to go the other way — no multiplication involved at all.
Frequently Asked Questions
- What is the formula for Celsius to Fahrenheit?
- °F = (°C × 9/5) + 32. Our converter does this calculation for you automatically.
- Does this converter support Kelvin?
- Yes, you can convert between Celsius, Fahrenheit, and Kelvin with high precision.