BACKGROUND: To identify physical measures that predict maximal handgrip strength (MHGS) and provide evidence for identifying lack of sincerity of effort when assessing upper extremity weakness. OBJECTIVE: This study investigated anthropometric measurements associated with MHGS of healthy young adults. METHODS: A convenience sample of 150 healthy adults ages 19 to 34 years old completed the MHGS assessment, which was measured using a Jamar dynamometer according to the protocol of the American Society of Hand Therapists, for both dominant and non-dominant hands. Several anthropometric data were collected, which included height, body weight, forearm length, forearm circumference, hand length, and hand width. RESULTS: Multivariable linear regression analysis indicated gender and hand width were uniquely and significantly associated with participants' MHGS for dominant and non-dominant hand and accounted for more than 60% of the variance, with R2=0.60, P<0.001 for the dominant hand model and R2=0.64, P<0.001 for the non-dominant hand model. CONCLUSIONS: Among the forearm and hand anthropometric measures, hand width is the best predictor of MHGS in both the non-dominant and dominant hands for healthy young adults.