Background/aim: Accurately measuring and recording the length or area of lesions affects the judgement of the forensic report, surgical wound management and, in some countries, the billing of health care services. The aim of this study was to determine whether the length and area of lesions described by physicians by estimation are accurate. Materials and methods: This study was designed as a cross-sectional descriptive study and was conducted with 494 participants consisting of internists and physicians at Ondokuz Mayıs University, Faculty of Medicine. The participants were asked to estimate the lengths or areas of 6 different shapes in the questionnaire form without using a measuring instrument. Results: Of the participants, 216 (43.7%) were interned physicians and 278 (56.3%) were physicians. Most 122 people (24.7%) answered the curved line shape with a length of 4 cm as “exact value”. The average of the values given by the internists to each shape was higher than the average of the values given by the physicians to each shape and was found to be further away from the true value. It was determined that more than half of the participants gave values above the actual length and area values of the shapes. It was observed that the rate of correct estimation of line shapes was higher than the rate of correct estimation of area shapes both as exact values and with ±10% margin of error. For line shapes, it was observed that the number of those who gave exact values decreased as the line length increased. Conclusion: When preparing forensic reports, determining surgical wound management and billing, estimated data should not be used in lesion description. It would also be useful to develop tools that will enable physicians to make measurements in terms of easy use.