There are several phrases that can be used as synonyms for the phrase "on one's own time". A popular option is "off-the-clock". This refers to activities that are done outside of regular work hours. Another phrase that can be used is "during one's free time". This encompasses any time that is not dedicated to work or other obligations. Additionally, "non-work hours" is a term that specifically refers to the time outside of normal work hours. "Personal time" is also an option, which alludes to any time that is dedicated to personal pursuits or leisure activities. Ultimately, there are several ways to describe the time one spends outside of work or obligations.
