Understanding whether a true change has occurred during the process of care is of utmost importance in lymphedema management secondary to cancer treatments. Decisions about when to order a garment, start an exercise program, and begin or end therapy are based primarily on measurements of limb volume, based on circumferences taken by physiotherapists using a flexible tape. This study aimed to assess intra-rater and inter-rater reliability of measurements taken by physiotherapists of legs and arms with and without lymphedema and to evaluate whether there is a difference in reliability when measuring a healthy versus a lymphedematous limb. The intra-rater reliability of arm and leg measurements by trained physiotherapist is very high (scaled standard error of measurements (SEMs) for an arm and a leg volume were 0.82% and 0.64%, respectively) and a cut-point of 1% scaled SEM may be recommended as a threshold for acceptable reliability. Physiotherapists can rely on the same error when assessing lymphedematous or healthy limbs. For those who work in teams and share patients, practice is needed in synchronizing the measurements and regularly monitoring their inter-rater reliability.