Convert between temperature scales
Use the formula: F = (C × 9/5) + 32. For quick mental math: double Celsius, subtract 10%, add 32. For example, 20°C: 40 - 4 + 32 = 68°F. Or remember key points: 0°C=32°F, 100°C=212°F.
Kelvin is the SI unit of temperature starting at absolute zero (-273.15°C). Scientists use Kelvin because there are no negative values and it's directly proportional to thermal energy. 0K means no molecular motion.
Celsius and Fahrenheit are equal at -40°. This is the only point where both scales intersect. It's a useful fact for checking your conversion calculations.
Fahrenheit was developed earlier (1724) and adopted by the British Empire. When the US gained independence, Fahrenheit was standard. The metric system came later, and the US never fully switched despite attempts.
Rankine is an absolute temperature scale using Fahrenheit-sized degrees. 0°R = absolute zero = -459.67°F. It's used in some US engineering applications, particularly in thermodynamics and aerospace.
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