Researchers have begun to explore the characteristics and risk factors for autistic burnout, but assessment tools are lacking. Our study comprehensively examined and compared the psychometric properties of the unpublished 27-item AASPIRE Autistic Burnout Measure (ABM), and personal and work scales of the Copenhagen Burnout Inventory (CBI) to evaluate their efficacy as screening measures for autistic burnout, with a group of 238 autistic adults. Exploratory factor analyses (EFA) revealed a 4-factor structure for the ABM and a 2-factor structure for the CBI personal scale (CBI-P). Factorial validity and dimensionality were examined with four exploratory models which indicated a unidimensional structure for the ABM with an overarching ‘Autistic Burnout’ construct, and multidimensional CBI-P structure comprising two subscales and overarching ‘Personal Burnout’ construct. Other reliability and validity indicators included Spearman correlations, analysis of variance, receiver operating characteristics, sensitivity, specificity, and intra-class correlations (ICC). The ABM and CBI-P were strongly correlated with depression, anxiety, stress, and fatigue. Unexpectedly, correlations between the burnout measures and camouflaging, and wellbeing measures were moderate. Potential overlap between burnout and depression and fatigue was examined through EFA, which supported convergent validity of the ABM and depression measure, while correlations and ICC analyses revealed mixed results. We concluded that the ABM and the CBI-P Emotional Exhaustion subscale were valid preliminary screening tools for autistic burnout. Testing with larger and more diverse autistic samples is required to further examine the psychometric properties of the ABM, and to understand the relationships between autistic burnout and depression, and masking.