Temperature Converter
Celsius, Fahrenheit and Kelvin are the three most widely used temperature scales in the world. Whether you are reading a US recipe, checking an American weather report or working through a physics problem, this calculator instantly and exactly converts any value to the scale you need.
結果
68 °F
Result
公式
°F = °C × 9/5 + 32 · K = °C + 273.15 · °C = (°F − 32) × 5/9
Celsius and Fahrenheit have different zero points and scale sizes: 0 °C (water's freezing point) equals 32 °F, and each Celsius degree is 1.8 times the size of a Fahrenheit degree. Kelvin uses the same scale size as Celsius but starts at absolute zero (−273.15 °C), so you simply add or subtract 273.15. The calculator converts every value to Celsius as an intermediate step, then to the target unit.
ステップ解説
- 1Enter the temperature value you want to convert.
- 2Choose the unit to convert from (Celsius, Fahrenheit or Kelvin) and the unit to convert to.
- 3Read the exactly converted temperature instantly.
計算例
100 °C (boiling point of water)
→ 100 × 9/5 + 32 = 212 °F, and 100 + 273.15 = 373.15 K.
98.6 °F (body temperature)
→ (98.6 − 32) × 5/9 = 37 °C.
0 K (absolute zero)
→ 0 − 273.15 = −273.15 °C, which is −459.67 °F.
Reference table
| Description | Celsius | Fahrenheit | Kelvin |
|---|---|---|---|
| Absolute zero | −273.15 | −459.67 | 0 |
| Freezing point of water | 0 | 32 | 273.15 |
| Room temperature | 20 | 68 | 293.15 |
| Body temperature | 37 | 98.6 | 310.15 |
| Boiling point of water | 100 | 212 | 373.15 |
Values rounded to two decimals; use the calculator above for other temperatures.
よくある間違い
- Assuming 0 °C equals 0 °F; 0 °F actually equals −17.8 °C.
- Forgetting that Fahrenheit degrees are smaller than Celsius degrees: each Fahrenheit degree is only 5/9 of a Celsius degree.
- Writing Kelvin with a degree sign ("°K"); the correct notation is simply "K" without a degree symbol.
活用シーン
- Converting a US recipe or oven temperature to Celsius.
- Interpreting a US weather report in Fahrenheit while travelling.
- Doing scientific calculations with Kelvin, for example in physics or chemistry.
よくある質問
Why does Kelvin exist alongside Celsius?
Kelvin is used in science and engineering because it starts at absolute zero, the point where there is no thermal energy left. This simplifies calculations involving temperature and energy, without negative values.
How can I quickly convert Celsius to Fahrenheit without a calculator?
A handy rule of thumb: double the Celsius value and add 30. This is not exact but usually only off by a few degrees from the real formula (× 9/5 + 32).
What is the difference of 1 degree Celsius in Fahrenheit?
A difference of 1 degree Celsius equals a difference of 1.8 degrees Fahrenheit, because the Fahrenheit scale has 180 degree steps between the freezing and boiling points of water compared to 100 for Celsius.
Can a temperature in Kelvin be negative?
No, the Kelvin scale starts at absolute zero (0 K = −273.15 °C), the lowest possible energy level. Negative Kelvin values do not exist in classical physics.
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