Background/objectives Handgrip strength is a critical indicator of overall health, particularly in older adults, and is associated with frailty, sarcopenia and risk of adverse health outcomes. Precise and reliable measurement instruments are necessary to ensure accuracy in personalised diagnostic evaluations. This study aimed to assess the inter-instrument reliability and agreement between the Jamar Plus+ digital and Jamar hydraulic dynamometers in measuring handgrip strength. Methods A cross-sectional study was conducted to assess the handgrip strength of older individuals in the community aged more than 60, using the Jamar Plus+ digital and Jamar hydraulic dynamometers. The inter-instrument reliability and agreement between the devices were evaluated using Intraclass Correlation Coefficients (ICCs) and Bland-Altman analysis. Results A total of 109 participants with a mean age of 66±5.3 years were included in this study. The Jamar Plus+ digital dynamometer recorded significantly higher handgrip strength measurements (27.0±7.1 kg) compared with the Jamar hydraulic dynamometer (21.0±6.7 kg). The ICCs between the two devices ranged from 0.67 to 0.70, indicating moderate reliability. Bland-Altman analysis revealed a consistent overestimation of handgrip strength by the Jamar Plus+ digital dynamometer, with systematic biases of 4.8 kg in men and 6.26 kg in women compared with the Jamar hydraulic dynamometer. Conclusion The Jamar Plus+ digital dynamometer consistently overestimated handgrip strength compared with the Jamar hydraulic dynamometer, but both devices demonstrated moderate reliability. The Jamar Plus+ showed greater responsiveness to variations in strength. Selecting appropriate diagnostic tools is crucial for optimising individualised health assessments in older adults. © Author(s) (or their employer(s)) 2025.