Objectives Gingival thickness (GT) has a great importance in periodontal flap design, gingival recession, and soft tissue esthetic. The aim of this study was to determine the reproducibility of PIROP ultrasonic biometer, which is specially designed for human GT measurements and to compare with the invasive transgingival probing technique. Materials and Methods GT was measured in 25 periodontally healthy volunteers both by PIROP and an endodontic spreader on the attached gingiva. Reproducibility was assessed by calculating standrad deviaton (SD) in five repeated measurements and Pearson correlation coefficient (r). Agreement between the two methods was evaluated based on Bland‐Altman limits of agreement (LoA). Results No systemic bias in GT was observed between the two methods. The repeatability of the PIROP was better than the spreader method (SD = 0.14 mm vs 0.20 mm, P < 0.001). With five repetitions, the measurement error of the PIROP was halved. The correlation among the repeated observations were strong (r = 0.86) for the ultrasonic, weak (r = 0.34) for the invasive method. The LoA between the two methods was −0.58 to +0.75 mm. Conclusion PIROP is a reliable device for GT measurements, but it is recommended to repeat the measurement a few times to improve the precision in individual case. Clinical Significance PIROP ultrasonic biometer could be used in routine practice to reliably measure the GT in noninvasive way. After short learning curve the measurement can be done quickly and conveniently.