In a wave, the path difference corresponding to a phase difference of $\varphi$ is:

For 2$\mathrm{\pi }$ phase difference, the path difference is $\mathrm{\lambda }.$

So, for $\mathrm{\varphi }$ phase difference, path difference will be $\frac{\mathrm{\lambda }}{2\mathrm{\pi }}\mathrm{\varphi }$.