Clock Jitter and Phase Noise
For a sine wave with a period $t_p$ the clock jitter or clock edge time error $t_j$ gives a phase error of $2 \pi t_j/t_p$ radians, where $2\pi$ represents a full period of a sine wave in terms of phase. The period $t_p$ of the sinusoid is an inverse of its frequency $f$, so the phase error can also be written as $2 \pi t_j f$. No matter if error is the peak error or the root mean square error, or whatever, as long as it is the same kind for both clock edge time error (jitter) and phase.