  By combining {\it ab initio} calculations and experiments we demonstrate how
the band gap of the transition metal tri-chalcogenide TiS$_3$ can be modified
by inducing tensile or compressive strain. We show by numerical calculations
that the electronic band gap of layered TiS$_3$ can be modified for monolayer,
bilayer and bulk material by inducing either hydrostatic pressure or strain. In
addition, we find that the monolayer and bilayer exhibits a transition from a
direct to indirect gap when the strain is increased in the direction of easy
transport. The ability to control the band gap and its nature can have an
impact in the use of TiS$_3$ for optical applications. We verify our prediction
via optical absorption experiments that present a band gap increase of up to
10\% upon tensile stress application along the easy transport direction.
