Background: Extraglottic airway devices (EADs) are frequently used airway devices, yet often they seal poorly, resulting in a functionally unacceptable leak. Optimal size selection of the EAD is therefore critical to the safe and effective use of an EAD. This review is designed to delineate the sizing recommendations of EADs and indicate the differences in order to make the optimal choice for device effectiveness and patient safety., Methods: We searched manufacturing' guidelines regarding size recommendations of EADs. Alternative size selection suggestions were obtained through an extensive literature search., Results: Most manufacturers offer different types and a wide range of (up to 8 different) sizes of EADs. Size ranges offered by manufacturers are most often based on weight, although some manufacturers offer alternative EADs based on a variety of patient variables (age, gender, height). Even 'one-size-fits-all' adult EADs have been introduced into clinical practice. Special formulae and methods are suggested to aid the clinician to find the optimal EAD size, especially for children., Conclusion: Selecting the appropriate size of an EAD is critical to optimal use, although applying the correct size of an EAD has been subject of controversy, as recommendations on sizing differ substantially and are far from a coherent and universal sizing system. Successful use of an EAD depends in part on appropriate size selection, in addition to clinical judgment, as well as patient anatomy and physiology. Standardization in the use of EAD sizes and a consensus about a consistent size systematic of EADs would benefit to promote a safer clinical practice in airway management.