The Kelvin scale is very similar to the Celsius scale - if the air temperature in Celsius rises by $10$ degrees, it also rises by ten degrees in the Kelvin scale. However, the scales differ in the location of the zero degree. The Kelvin scale does not have minus degrees at all, because based on this scale, the temperature $0$ is the lowest possible temperature in the Universe (on the Celsius scale, it corresponds to the temperature $-{273.15}^{\circ }\text{C}$). That is why this scale is useful for researchers who are confused by minus signs in their calculations. In the Kelvin scale, the degree sign is not placed behind the temperature values, and the symbol is $\text{K}$, for example $273\text{K}$, which in the Celsius scale corresponds to the temperature $0^{\circ }\text{C}$.

Converting from the Celsius scale to the Kelvin scale is easy: for this you need to add $273$ to the Celsius temperature. If you want to convert the other way, i.e. from the Kelvin scale to the Celsius scale, you have to subtract $273$, for example ${20}^{\circ }\text{C}$ is $20+273=293\text{K}$ and $53K$ is $53-273=-{220}^{\circ }\text{C}$.

The Fahrenheit scale is not very common in the world - the best-known country that uses it is the United States. Like Celsius, temperatures on this scale are denoted by a number followed by a degree sign and the $\text{F}$ symbol, such as ${50}^{\circ }\text{F}$. On this scale, ice melts at ${32}^{\circ }\text{F}$ and water boils at ${212}^{\circ }\text{F}$. $0^{\circ }\text{F}$ corresponds to $-{18}^{\circ }\text{C}$ on the Celsius scale.

In order to convert the temperature from the Fahrenheit scale to the Celsius scale, one should subtract $32$ from the thermometer reading and divide the result by $1.8$, for example $(212-32)/1.8=100$ or ${212}^{\circ }\text{F}$ is ${100}^{\circ }\text{C}$. You can also do it the other way around, but then you must first multiply by $1.8$ and then add $32$, for example $20\cdot 1.8+32=68$, i.e. ${20}^{\circ }\text{C}$ is ${68}^{\circ }textF$.