A wedge is really an inclined plane adapted to different applications. The mechanical advantage comes from the ratio of the length to the slope. A more “keen” or sharp wedge will offer more mechanical advantage. As with the inclined plane, the tradeoff is between the distance moved and the height gained.
When the wedge is pushed or driven into a narrow space, it creates a force that is perpendicular to the inclined surface of the wedge. This force is greater than the input force applied to the wedge, providing a mechanical advantage. The mechanical advantage of a wedge is calculated by dividing the length of the sloping side of the wedge by its thickness. The longer and thinner the wedge, the greater the mechanical advantage it provides.