The Q temperature coefficient is a measure of temperature sensitivity based on the chemical reactions.
The Q is calculated as:
where;  
: R is the rate
: T is the temperature in Celsius degrees or kelvin.
Rewriting this equation, the assumption behind Q is that the reaction rate R depends exponentially on temperature:
Q is a unitless quantity, as it is the factor by which a rate changes, and is a useful way to express the temperature dependence of a process.
For most biological systems, the Q value is ~ 2 to 3.