The manual crack meter is a simple and effective instrument designed for measuring and monitoring the evolution of cracks in civil structures and infrastructure. The device consists of two overlapping plates: a lower plate graduated in millimeters and an upper transparent plate with a reference grid, which slide relative to each other allowing direct reading of relative displacements. Installed across the crack, the crack meter allows monitoring over time of opening, closure, and relative displacement, both in the horizontal and vertical directions, with immediate reading and without the need for additional instrumentation. Thanks to its simplicity, robustness, and low cost, it represents the ideal solution for preliminary inspections, manual monitoring, and applications requiring visual assessment with direct and easily interpretable measurement.