Objective. Grip strength testing offers a mechanism to identify patients in whom frailty might be present, discriminate between robust elderly and vulnerable younger patients, and can be used as a tool to track changes in muscle bulk over the course of an inpatient stay. We compared gold-standard quantitative grip strength measurement to a low-tech alternative, a manual bedside sphygmomanometer. Design. Under supervision, subjects performed hand-grip strength testing with each instrument. A mean score is calculated from three measurements on the dominant and nondominant hand. Setting. Testing was performed in a tertiary centre in Perth, Western Australia, in both outpatient clinics and intensive care units. Participants. 51 adult pre-operative surgical outpatients were assessed, alongside 20 intensive care inpatients identified as being weak. Main outcome measures. A statistical correlation between the two measures was evaluated. Feasibility, safety, and convenience were also assessed in outpatient and bedside settings. Results. Highly correlated results in both tertiary surgical outpatients (rs = 0.895, p ≤ 0.001 , N = 102; r (100) = 0.899, p ≤ 0.001 ) and weak intensive care patients (rs = 0.933, p ≤ 0.001 , N = 39 r (37) = 0.935, p ≤ 0.001 ) Conclusions. Modifying a manual bedside sphygmomanometer to measure grip strength is feasible and correlates well with a formal dynamometer in preadmission surgical patients and weak patients in the intensive care unit. The use of an existing, safe, and available device removes barriers to the measurement of weakness in patients and may encourage uptake of objective measurement in multiple settings.