With the emergence of research investigating the role of gamma-aminobutyric acid (GABA) in neurological and neuropsychiatric diseases, it is important to understand the variability in GABA as measured through magnetic resonance spectroscopy (MRS) and how this variability may affect the interpretation of results. This review addresses methodological sources of variation documented in the current literature on the measurement of GABA. GABA differences related to hardware, acquisition, post-processing and quantification are discussed, and methods to account for or remove this variability are highlighted. Additionally, factors such as time, age, biological sex, hormones, and brain region, which may affect GABA MRS, are reviewed to aid in study design. This review is meant to assist in measuring GABA comparably between studies and improve GABA methodology to allow the use of GABA MRS in a clinical setting in the future.