Background/aim: This study aimed to assess the correlations of actual epidural depth (ND) and ultrasound estimated epidural depth in the paramedian sagittal oblique plane (ED/PSO) and transverse median plane (ED/TM) with the abdominal girth (AG), body mass index (BMI), and weight of patients. Materials and methods: One hundred and thirty patients of either sex scheduled for unilateral inguinal hernia repair were enrolled. ED/PSO and ED/TM were assessed with a 2-5 MHz curved array probe at the L3-4 intervertebral space. The epidural needle was marked with a sterile marker upon locating the epidural space. The ND was assessed by measuring the distance from the sterile marker to the tip of the epidural needle with a linear scale. Anthropometric measures of the patients were recorded. Results: ED/PSO was 49.6 ± 7.9 mm, ED/TM was 49.5 ± 7.9 mm, and ND was 50.0 ± 8.0 mm. AG was 99.8 ± 12.9 cm. The Pearson correlation coefficient between ND and ED/PSO was 0.997 and with ED/TM was 0.996 (P