To provide reference data for the Cumberland Ankle Instability Tool (CAIT) and to investigate the prevalence and correlates of perceived ankle instability in a large healthy population. Cross-sectional observational study. University laboratory. Self-reported healthy individuals (N=900; age range, 8-101y, stratified by age and sex) from the 1000 Norms Project. Not applicable. Participants completed the CAIT (age range, 18-101y) or CAIT-Youth (age range, 8-17y). Sociodemographic factors, anthropometric measures, hypermobility, foot alignment, toes strength, lower limb alignment, and ankle strength and range of motion were analyzed. Of the 900 individuals aged 8 to 101 years, 203 (23%) had bilateral and 73 (8%) had unilateral perceived ankle instability. The odds of bilateral ankle instability were 2.6 (95% confidence interval CI, 1.7-3.8; P<.001) times higher for female individuals, decreased by 2% (95% CI, 1%-3%; P=.001) for each year of increasing age, increased by 3% (95% CI, 0%-6%; P=.041) for each degree of ankle dorsiflexion tightness, and increased by 4% (95% CI, 2%-6%, P<.001) for each centimeter of increased waist circumference. Perceived ankle instability was common, with almost a quarter of the sample reporting bilateral instability. Female sex, younger age, increased abdominal adiposity, and decreased ankle dorsiflexion range of motion were independently associated with perceived ankle instability.