The three temperature scales
Celsius is used almost everywhere for daily weather, with water freezing at 0° and boiling at 100°. Fahrenheit, common in the United States, puts freezing at 32° and boiling at 212°. Kelvin is the scientist's scale: it starts at absolute zero, the coldest anything can get, and shares the same step size as Celsius.
The formulas, if you like
°C = (°F − 32) × 5/9
K = °C + 273.15
A quick mental trick for Celsius to Fahrenheit: double it and add 30. It is not exact, but it gets you close enough to know whether to grab a coat.
Everyday reference points
Body temperature is about 37°C (98.6°F). A warm summer day sits around 30°C (86°F). Water boils at 100°C (212°F). These anchors help the numbers feel real rather than abstract.
Frequently asked questions
What is 100°F in Celsius?
About 37.8°C — just above body temperature.
What is room temperature?
Usually around 20–22°C, which is about 68–72°F.
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