To monitor wound healing, it is essential to obtain accurate and reliable wound measurements. Various methods have been used to measure wound size including three-dimensional (3D) measurement devices enabling wound assessment from a volume perspective. However, the currently available methods are inaccurate, costly, or complicated to use. As a consequence, we have developed a 3D-wound assessment monitor (WAM) camera, which is able to measure wound size in three-dimension and to assess wound characteristics. The aim of the study was to assess the intrarater and interrater reliability of the 3D wound measurements using the 3D camera and to compare these with traditional measurement methods. Four raters measured 48 wounds using the 3D camera, digital imaging method (2D area), and gel injection into the wound cavity (volume). The data were analyzed using linear mixed effect model. Intraclass and interclass correlation coefficient (ICC) and Bland–Altman plots were used to assess intrarater and interrater reliability for the 3D camera and agreement between the methods. The Bland–Altman plots for intrarater reliability showed minor differences between the measurements, especially the 3D area and perimeter measurements. Moreover, ICCs were very high for both the intrarater and interrater reliability for the 2D area, 3D area, and perimeter measurements (ICCs > 0.99), although slightly lower for the volume measurements (ICC = 0.946–0.950). Finally, a high agreement was found between the 3D camera and the traditional methods (2D area and volume) assessed by narrow 95% prediction intervals and high ICCs above 0.97. In conclusion, the 3D-WAM camera is an accurate and reliable method, which is useful for several types of wounds. However, the volume measurements were primarily useful in large, deep wounds. Moreover, the 3D images are based on digital technology and therefore carry the possibility for use in remote settings.