The coastline paradox, which suggests that coastlines have indefinite lengths, is a widespread and misleading concept that has endured in scientific literature for over 50 years. This paper argues that the length of a coastline is real and finite. The measurement of coastlines allows for the quantification of coastline dynamics and engineering responses to these changes. The real difficulties in measuring sometimes complex coastal shapes have taken the appearance of an unreal impossibility. The paradox is resolved using three methods. The first examines definitions used to establish the features to which “coastline” refers. The second applies these definitions to the measurement of real coastlines. Finally, a geometrical analysis is carried out to resolve the paradox mathematically. The purpose of this paper is to help resolve the paradox and reduce confusion surrounding the topic, which will be of direct use for coastal communities and planners to assess and respond to coastline changes and sea-level rise.