Purpose <p>To establish a retinal break localization (RBL) formula and determine its reliability and influencing factors.</p> Methods <p>A trigonometric function was used to develop a formula for the distance CB from the limbus (C) to the apex of the retinal breaks (B) based on a model eye, ultra-wide-field fundus (UWF) images, and optical biometric data. The CB values of 43 eyes were compared with the measurement obtained during operation, CB1. The influential and correlating factors analyzed were the axial length (AL), types of the break, macula (off or on), anterior chamber depth (ACD), and white to white corneal diameter (WTW) measurements.</p> Results <p>Compared to CB1, CB was longer in the group of all cases (<i>p</i> = 0.032) and the groups with AL ≥ 26&#xa0;mm (<i>p</i> = 0.007). In the three other AL groups (AL &lt; 26, 25, 24&#xa0;mm), there were no significant differences between CB and CB1 (<i>p</i> = 0.200, 0.599, 0.246). The categories of the breaks and macula had no significant effect on the reliability of the formula (<i>p</i> = 0.121, 0.085). There was a positive correlation between the AL and the difference between CB and CB1 (Pearson correlation = 0.662, <i>p</i> &lt; 0.001).</p> Conclusion <p>The proposed formula has value for locating retinal breaks in cases of AL less than 26&#xa0;mm and provides a new quantitative metric.</p>