A support surface in mechanical engineering is the area of ​​contact between two objects. It is usually used in reference to bolted joints and bearings, but can be applied to a wide variety of engineering applications.

In a screw, the "support area" refers generically to the underside of the head.[1]​ Strictly speaking, the support area refers to the area of ​​the screw head that rests directly on the workpiece being fastened.[2]​.

For a cylindrical bearing it is the projected area "perpendicularly with respect to the applied force.[3]​.

In a spring, the support area refers to the amount of area on the upper or lower surface of the spring in contact with the part that constrains the elongation of the spring.[4]​.

Machine tool tracks, such as dovetail slides, drawer guides, prismatic tracks, and other types of machine slides, are also support surfaces.