Sarcopenia is a disease related to accelerated loss of skeletal muscle and subsequent decline in functional capacity. It affects approximately 13% of the world's population aged over 60 years. Sarcopenia is primarily managed and prevented through a combination of exercise prescription combined with appropriate nutritional strategies. This review outlines diagnostic and case finding/screening tools for age-related (primary) sarcopenia used in research and clinical practice. Diagnostic tools critically reviewed include those of the: European Workgroup for Sarcopenia (EWGSOP) versions 1 and 2; Asian Working Group for Sarcopenia (AWGS) versions 1 and 2; Foundation for the National Institutes of Health (FNIH); and the Sarcopenia Definition and Outcomes Consortium (SDOC). Criteria used by diagnostic tools (muscle mass, muscle strength and physical functioning/performance) are also detailed. Case-finding tools include the SARC-F questionnaire, Ishii's formula and Goodman's screening grid. Additionally, this review discusses the strengths and weaknesses of each diagnostic and case-finding tool, and examines their ability to reliably predict adverse clinical outcomes and patient responses to potential therapies.