handing

Handing is a term used in manufacturing, architecture, and product design to describe the left‑ or right‑hand orientation of a component with respect to its installation or operation. It is commonly applied to doors, windows, cabinets, and other components that mirror along a vertical axis, where a left-hand variant and a right-hand variant are not interchangeable.

The handedness of a door is typically determined by the side on which the hinges are mounted relative to the door when it is closed. A door with hinges on the left when viewed from the exterior is called a left-hand door; a door with hinges on the right is a right-hand door. Some conventions use the interior view, or specify left-hand reverse (LHR) versus right-hand reverse (RHR) depending on whether the door is swung into or out of the room. Regions and manufacturers may vary in their standard definitions, so installation drawings should indicate the exact convention used.

Non-handed or reversible components are designed to be installed on either side without modification; these are valued for flexibility in stock and installation. For handed products, changing orientation often requires swapping hardware and may affect clearances and operation.

In practice, handing affects product drawings, ordering, and field installation. It is important to specify handing in purchase orders and construction documents to ensure the correct variant is supplied and fitted, avoiding interference with frames, jams, or finishes. The concept also extends to other mirrored components, including windows, cabinetry doors, and some automotive and appliance parts.