To evaluate the NIH All of Us Research Program database as a potential data source for studying allostatic load and stress among adults in the United States (US). We evaluated the All of Us database to determine sample size significance for original-10 allostatic load biomarkers, Allostatic Load Index-5 (ALI-5), Allostatic Load Five, and Cohen's Perceived Stress Scale (PSS). We conducted a priori, post hoc, and sensitivity power analyses to determine sample sizes for conducting null hypothesis significance tests. The maximum number of responses available for each measure is 21 participants for the original-10 allostatic load biomarkers, 150 for the ALI-5, 22476 for Allostatic Load Five, and n = 90583 for the PSS. The NIH All of Us Research Program is well-suited for studying allostatic load using the Allostatic Load Five and psychological stress using PSS. Improving biomarker data collection in All of Us will facilitate more nuanced examinations of allostatic load among US adults.