Convert degrees Fahrenheit to kelvin

Temperature does not work that way — the scales have different zero points, so there is no single ratio between them. One degree Fahrenheit is not a fixed number of kelvin; you have to apply both a scale and an offset. At the freezing point of water, 273.15 K corresponds to the same physical temperature.

You need both a multiplication and an addition, because Celsius, Fahrenheit and kelvin do not share an origin. That is what makes temperature different from every other unit conversion — length, mass and volume all pass through zero at the same point, so a single factor works. Temperature does not.

One degree Fahrenheit is 32 is freezing, 68 is a mild room, 98.6 is body temperature. Fahrenheit puts water's freezing point at 32 and boiling at 212. It remains the civil scale in the United States and a few Caribbean territories.

One kelvin is 273.15 is freezing, 293 is a mild room. The kelvin starts at absolute zero and shares Celsius's degree size, so it has no negative values and takes no degree symbol. It is the SI base unit for temperature.

Because a temperature and a temperature difference are different things. Converting 10 °C gives 50 °F, but a rise of 10 °C is a rise of 18 °F — the offset applies to a point on the scale, not to an interval. For differences, use only the scaling part: multiply by 9/5 going from Celsius to Fahrenheit, and leave the +32 out. Mixing these up is the single most common temperature error.

Yes. The relationships between Celsius, Fahrenheit and kelvin are defined exactly, not measured, so the conversion is precise to as many digits as you care to keep. The results here are shown to seven significant figures, which is far beyond what any thermometer can resolve.