Stagnation pressure is the static pressure a gas retains when brought to rest isentropically from Mach number M.
or, assuming an isentropic process, the stagnation pressure can be calculated from the ratio of stagnation temperature to static temperature:
where:
: is the stagnation pressure
: is the static pressure
: is the stagnation temperature
: is the static temperature
: is the ratio of specific heats
The above derivation holds only for the case when the gas is assumed to be calorically perfect (specific heats and the ratio of the specific heats  are assumed to be constant with temperature).