The study was conducted to evaluate correlation between the endometrial length and thickness on two-dimensional (2D) ultrasound to the endometrial volume calculated by three-dimensional (3D) ultrasound virtual organ computer-aided analysis (VOCAL). All patients having transvaginal scans (TVSs) at our center were included and patient having fluid in endometrium, polyp, fibroid, and pregnancy were excluded. Two-dimensional measurements of uterine length, endometrial length, effective endometrial length, endometrial thickness, and endometrial breadth in transverse section were taken. Endometrial volume was taken by 3D ultrasound software VOCAL with rotational step of 9°. A multivariate regression analysis was carried out using Excel add in stat tool software, and the 2D parameters taken were correlated with the volume obtained by VOCAL, and an equation for volume is also derived with the same multivariate regression and compared with the volume obtained by VOCAL. The analysis shows that the equation is significant as R² (coefficient of determination) is significant (F statistics is 39.26 whose p value is <0.0001), and almost all the regression coefficients are significant except that for endo breadth in transverse section. R² = 0.5241 indicates that almost 52% of the variation in the endometrial volume has been explained by the considered independent variables in the equation. The scatterplot graph (Fig. 1) shows a positive relationship, and no outlier is observed. Also, the residue is normally distributed which is observed in the graph. The residual graph follows normality assumption and so the equation is applicable (Fig. 2). According to these results, the most correlating 2D parameters with 3D calculated endometrial volume were endometrial length and endometrial thickness. This also conveys that when endometrium is evaluated by 2D ultrasound for its receptivity, it is essential to include endometrial length along with endometrial thickness for better prediction or evaluation of endometrial receptivity.