Devices and methods for performing a skin biopsy are discussed herein. The skin biopsy device provides for consistent depth and shape, such as by reducing or eliminating operator error or inter-operator variability by generating the same forces across multiple uses. The skin biopsy device can also eliminate puckering of wound closures by incorporating a fusiform blade (e.g., elliptical blade or a diamond-shaped blade). The skin biopsy device includes a casing, a firing pin, a retaining rod, and a blade. The retaining rod holds the blade or can attach to a punch biopsy. The firing pin generates and impacts the retaining rod with a force necessary to drive the blade a given depth into a target tissue to obtain a biological sample.