What is a Temperature Converter?
The temperature converter switches between Celsius (°C), Fahrenheit (°F), and Kelvin (K).
How it's calculated
°F = °C × 9/5 + 32
°C = (°F − 32) × 5/9
K = °C + 273.15
Units that are easy to mix up
| Units | Why it's confusing | How to tell them apart |
|---|---|---|
| °C vs K | Both are temperature scales | K starts at absolute zero (0K=-273.15°C), °C is anchored to water |
| °F vs °C | Numbers look very different | °C×9/5+32=°F; they only match at -40 degrees |
Why is Fahrenheit such a strange scale?
In 1724, Daniel Fahrenheit set 0° as the coldest temperature he could reliably reproduce (a salt-and-ice brine mixture) and 96° as roughly human body temperature. The now-familiar 32° freezing and 212° boiling points of water were simply consequences of that original scale, not the intended design.
Celsius, defined by Anders Celsius in 1742, split water's freezing and boiling points into 0 and 100 — but interestingly, his original scale was inverted, with boiling at 0° and freezing at 100°. It was flipped to today's convention after his death.
Good to know
- Celsius and Fahrenheit intersect at exactly one point: −40°. -40°C equals -40°F — the only temperature where the two scales agree.
- The US, along with a small handful of other countries, is one of the few places that still uses Fahrenheit as the everyday standard — largely because it was already entrenched when the rest of the world adopted Celsius.
- Fahrenheit's advantage is that everyday weather roughly spans 0 to 100, making it fairly intuitive as a 'feels-like' scale for daily temperatures.
- Kelvin never uses the degree symbol (°) — it's written as 300K, not 300°K, because it's an absolute scale starting at true zero (0K = -273.15°C).
- Quick mental conversion: double the Celsius value and add 30 for a rough Fahrenheit estimate. 20°C → 70°F (actual: 68°F) — close enough for everyday use.
Frequently asked questions
Q. What is 100°F in Celsius?
About 37.8°C — close to human body temperature, reflecting Fahrenheit's original reference point.
Q. What Celsius setting matches a 350°F oven?
About 177°C. Most home ovens round to 180°C.
Q. What is Kelvin used for?
Scientific and engineering calculations, and lighting color temperature notation (e.g., 6500K daylight).