The relation between a non-Sl unit of magnetic field gauss and the Sl unit tesla is 1 tesla = gauss.

SI unit of the magnetic field (B) is weber/meter² $\left({\mathrm{Wbm}}^{-2}\right)$ or tesla.

The CGS unit of magnetic field (B) is gauss where $1\mathrm{gauss}={10}^{-4}\mathrm{tesla}$.

From the above explanation, we can see that the relation between tesla and gauss is $1\text{ tesla }={10}^4\text{ gauss }$

Key Point: 

Magnetic field strength or magnetic field induction or flux density of the magnetic field is equal to the force experienced by a unit positive charge moving with unit velocity in a direction perpendicular to the magnetic field.