Perceived stigma among patients with alopecia is associated with impaired quality of life; however, the magnitude of laypersons' stigma toward individuals with alopecia is unknown.To determine the prevalence and magnitude of laypersons' stigma toward individuals with varying degrees of alopecia and whether stigma increases with increased severity of alopecia.This was a cross-sectional study using an internet survey administered to a convenience sample of adult respondents in the US participating on the Amazon Mechanical Turk platform. Portrait images of 6 individuals without hair loss were created using artificial intelligence and stock images. Each portrait was edited to create 2 additional versions, 1 with scalp hair loss and 1 with complete hair loss, for a total of 18 images. On January 9 to 10, 2020, the survey presented each internet respondent with 1 randomly selected portrait to be used in answering a series of stigma-related questions from 3 domains: stereotypes, social distance, and disease-related myths; the third domain was presented only to respondents who believed that the individual pictured had a medical condition.The main outcome was the prevalence and magnitude of stigma of laypersons toward individuals with alopecia and the percentage of laypersons who believed the individual pictured had a medical condition as recorded in survey responses.The survey was completed by 2015 respondents (99.9% completion rate) with a mean age of 37 (range, 18-78) years; 1014 (50.3%) were men; 1596 (79.2%) were White; and 1397 (69.3%) had a college or postcollege education. Endorsement of every stigma item increased as alopecia severity increased (2.4%-27.6%). Absolute change on the stereotype (0.5-0.6) and social distance scales (0.2-0.5) also increased, indicating more stigma. The percentage of respondents believing the individual pictured had a medical condition increased as alopecia severity increased (33.6%-75.7%; P .001). Among the subgroup of respondents who were asked to rate their agreement with disease-related myths, the absolute change on the myth scale decreased as alopecia severity increased, indicating decreased stigma (-0.7 to -1.2).This cross-sectional survey study found that stigmatizing attitudes of laypersons toward patients with alopecia exist across a multitude of social and professional scenarios. Stigma prevalence and magnitude vary by alopecia severity and possibly by whether alopecia is believed to be a medical condition.