butt hinge
A kind of hinge used in hanging doors, lid, covers, etc.; so named because fastened on the edge of the door, which butts against the frame, stop molding, and casing, instead of on its face, like the strap hinge; also called a butt.
butt hinge: the hidden workhorse of every swinging door
A butt hinge is a cylindrical hinge mortised into the edge, or butt, of a door and its frame. Unlike surface-mounted hinges, the butt hinge sits flush with the wood grain, leaving only a narrow vertical line visible when the door closes. This design puts the hinge pin parallel to the door's movement, allowing the door to swing smoothly while the hinge remains largely concealed.
The hinge consists of two identical leaves, each with a hollow barrel at one end. These barrels interlock around a removable pin, usually made of steel or stainless steel. Standard residential hinges are typically 3.5 inches tall and 1.125 inches wide when closed, with the pin diameter ranging from 5/32 inch to 1/4 inch depending on load rating. Heavier doors, cabinet openings, and industrial applications use larger hinges with thicker leaves and wider barrels.
Installation requires precise chiseling of matching mortises into both door and frame. The mortise must be the exact thickness of the hinge leaf so that both leaves sit flush with the surface; if either mortise is too deep, the door will not close properly or will bind. This is where most installation errors occur. Professional carpenters mark both door and frame together to ensure the mortises align perfectly.
Variants and selection
Standard butt hinges come in plain steel, brushed brass, and stainless steel. Template hinges have pre-drilled screw holes to speed installation. Ball-bearing butt hinges have races around the pin to reduce friction and wear, and are preferred for heavy doors or frequent opening. Architectural hinges rated for fire doors or exterior exposure are available in various materials. Weight capacity depends on hinge size and material; a 3.5-inch steel butt hinge typically supports 50 to 80 pounds per pair.
The term "butt" comes directly from the joint itself: the edge of the door literally butts against the frame and stops. This distinguishes the butt hinge from older strap hinges, which are fastened to the face of the door with long straps extending across the wood surface. Butt hinges became standard in residential and commercial construction because they are stronger, more durable, and aesthetically cleaner than surface-mounted alternatives, and they tolerate wear better than weaker hinge styles.