The massive OB-type binary \sigma Ori AB is in the centre of the very young \sigma Orionis cluster .
I have computed the most probable distances and masses of the binary for several ages using a dynamical parallax-like method .
It incorporates the BVRIH -band apparent magnitudes of both components , precise orbital parameters , interstellar extinction and a widely used grid of stellar models from the literature , the Kepler ’ s third law and a \chi ^ { 2 } minimisation .
The derived distance is 334 ^ { +25 } _ { -22 } pc for an age of 3 \pm 2 Ma ; larger ages and distances are unlikely .
The masses of the primary and the secondary lie on the approximate intervals 16–20 and 10–12 M _ { \odot } , respectively .
I also discuss the possibility of \sigma Ori AB being a triple system at \sim 385 pc .
These results will help to constrain the properties of young stars and substellar objects in the \sigma Orionis cluster .