BACKGROUND: Although the World Professional Association for Transgender Health has provided international, multidisciplinary, evidence-based standards of care for various aspects of transgender health care, there is a lack of evidence-based guidelines for facial feminization surgery, including chondro laryngoplasty. The aim of this study was to define the recommended maximum laryngeal prominence size in adult females to propose an evidence-based laryngeal prominence size standard for chondrolaryngoplasty in male-to-female transgender individuals. METHODS: This cross-sectional study was conducted in a tertiary care hospital. The study sample consisted of cisgender patients aged 18 to 60 years old with no history of surgery or radiotherapy in the head and neck area who visited the Otolaryngology/Head and Neck Surgery outpatient clinic. Laryngeal prominence size data were collected using three-dimensional scanning of the head and neck area. RESULTS: Seventy-nine participants, 43 males and 36 females, were included in data analysis. Laryngeal prominence size was larger in male participants (median, 0.16 mm; range, 0 to 9.40 mm) than in female participants (median, 0.00 mm; range, 0 to 1.24 mm) (p < 0.001). The proportion of participants with a laryngeal prominence size larger than 0 mm was greater in male participants (55.81 percent) than in female participants (22.22 percent) (p = 0.002). CONCLUSIONS: To the authors' knowledge, this is the first study to assess laryngeal prominence size in the general population. Their results suggest that 2 mm would be the recommended maximum laryngeal prominence size in females. Therefore, a laryngeal prominence size standard of 2 mm could be considered for chondrolaryngoplasty in male-to-female transgender individuals.