Gender-affirming hormones have been shown to improve psychological functioning and quality of life among transgender and nonbinary (trans) people, yet, scant research exists regarding whether and why individuals take more or less hormones than prescribed. Drawing on survey data from 379 trans people who were prescribed hormones, we utilized multivariable logistic regression models to identify factors associated with hormone-dosing behaviors and content analysis to examine the reasons for dose modifications. Overall, 24% of trans individuals took more hormones than prescribed and 57% took less. Taking more hormones than prescribed was significantly associated with having the same provider for primary and gender-affirming care and gender-based discrimination. Income and insurance coverage barriers were significantly associated with taking less hormones than prescribed. Differences by gender identity were also observed. Addressing barriers to hormone access and cost could help to ensure safe hormone-dosing behaviors and the achievement trans people's gender-affirmation goals.