The apical termination of obturation is the most important factor influencing the success of root canal treatment (RCT). Working length (WL) is the key element in achieving this. OBJECTIVE The aim of this study is to compare and evaluate the preoperative estimated WL with conventional radiograph and with grid radiograph, with reference to electronic apex locator (EAL) in single-rooted teeth. METHODS Thirty permanent anterior teeth with complete root formation indicated for RCT were included in this study. METHODS Conventional radiograph (Group 1) and conventional radiograph with external grid (Group 2) were made before access opening. WL with EAL (Group 3) was determined after access opening. METHODS The statistical package for the social sciences (SPSS) version 16.0 (SPSS Inc., Chicago, IL, USA) was used to compare the WLs of three groups, and the statistical significance was considered to be P ≤ 0.05. ANOVA, post hoc test were made to measure the intergroup comparison, and Pearson correlation values were obtained. CONCLUSIONS The results of the study showed a higher correlation between grid WL and apex locator WL than conventional WL and apex locator WL. Preoperative metrics with radiographic grid along with the apex locator is a better measuring tool compared to the conventional radiographic WL in a single-rooted tooth.