Parts of a Hinge – Leaf, Knuckle, Pin and Hinge Types

All 9 parts on the diagram

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Butt hinge 5

Leaf Some books call the leaves flaps.
Knuckle The knuckles of the two leaves alternate and interlock. Together they make the barrel.
Pin Also called a pintle. Here it is lifted part of the way out.
Tip Makers list ball tips and button tips. The tip and the pin are often made in one piece.
Screw hole The holes are countersunk for the screw heads.

Other hinges 4

Strap hinge It is the oldest kind of hinge.
T-hinge Also spelled tee hinge. It is used mainly on outside doors and gates.
H-hinge It is fixed to the face of a door. The door sits flush with its frame.
Continuous hinge (piano hinge) It spreads the load along the whole edge.

How this list was compiled: Every name checked on 2026-09-30, a name kept only where two independent sources use it: Wikipedia, text only, Hinge, https://en.wikipedia.org/wiki/Hinge (pin or pintle, knuckle, leaf, barrel; butt, continuous or piano, H and tee hinges); J. Hay, Woodwork (1976), https://archive.org/details/woodwork0000hayj (two leaves or flaps, a knuckle and a steel pin; countersunk screw holes; butt, tee and strap hinges); N. E. Berry, Architectural Hardware (2006), https://archive.org/details/architecturalhar00berr (knuckle, loose pin, a pin topped with a finial, the strap hinge and its T- and H- variations); Dictionary of Building Preservation (1996), https://archive.org/details/dictionaryofbuil0000unse_q4a2 (knuckle, leaf, loose-pin hinge, strap hinge, T-hinge, H-hinge); a hinge maker's catalog of 1937, https://archive.org/details/stanleyhardware00stan (leaves, screw holes, tip and pin made in one piece, ball tip and button tip, barrel); a second maker's builders' hardware catalog, https://archive.org/details/BuildersHardwareCatalogNo.20_775 (door leaf, jamb leaf, five knuckle, button tip); and the Steel Door Institute glossary, https://steeldoor.org/glossary/ (continuous hinge). The books and catalogs were read through archive.org's full-text search. Hints and detail lines are in our own words. Licence: own work

The drawing: Drawn for this site on 2026-09-30 from plain geometry; no maker's hinge, nothing traced. Licence: own work

How it works

The hinge on most room doors is a butt hinge: two leaves, a row of knuckles and a pin. The first drawing names its parts, and the second shows four other hinges with shapes of their own.

Read the full guide

The butt hinge

Each leaf is a flat plate with countersunk screw holes. Along its inner edge are knuckles, hollow rounds that interlock with the knuckles of the other leaf. The pin slides through all of them and holds the leaves together, with a tip on its end. Here the pin is lifted so it can be seen.

Four other hinges

A strap hinge has two long leaves fixed to the face of a door or gate. A T-hinge has one upright leaf and one long one. An H-hinge has two tall leaves joined at the middle. A continuous hinge, or piano hinge, runs the whole length of the edge.

Leaf or knuckle? The leaf is flat and takes the screws; the knuckle is round and takes the pin.

Questions and answers

What are the parts of a door hinge called?

Two leaves, the knuckles and a pin. One leaf is screwed to the door and the other to the frame. The knuckles of the two leaves interlock, and the pin runs through them. Many pins end in a tip.

What is the pin in a hinge called?

The hinge pin, or pintle. It holds the two leaves together. On a loose pin hinge it can be taken out to unhinge the door; on others it is fastened in place.

What is the round part of a hinge called?

Each round is a knuckle. The whole row of knuckles, with the pin inside it, is called the barrel.

What is a butt hinge?

A hinge made to be set into the edge of a door and into its frame. It is also called a mortise hinge, and it is the usual hinge on a room door.