A butt hinge does two things at once: it carries the dead weight of the door, and it resists the leverage of that weight trying to pull the top hinge out of the jamb. Undersize it and the top screw fixings work loose long before anything visibly breaks. Almost every "faulty hinge" we are asked about is one of three things — not enough hinges, the wrong bearing, or screws that never reached solid timber.
The working trade convention, which is what most joiners and door manufacturers apply:
| Door | Hinges |
|---|---|
| Cabinet and cupboard doors, light and short | 2 |
| Standard internal door, hollow core, up to about 2040 mm | 2 – 3 |
| Solid core internal door | 3 |
| External, entry, or any door over about 2040 mm | 3 – 4 |
| Heavy timber, glazed, or fire-rated doorsets | 4, or as specified by the doorset manufacturer |
The third hinge goes near the top — conventionally about 250 mm below the second one, not in the middle. The leverage that pulls a door out of square acts at the top of the door, so that is where the extra hinge earns its keep. A hinge placed at mid-height mostly stops the stile bowing; it does very little for sag.
Fire and smoke doorsets, and most engineered or heavy glazed doors, are certified as complete assemblies. The number, size and type of hinge is part of that certification, and the door manufacturer's schedule overrides any general rule of thumb — including this one.
Hinge size is quoted as leaf height. Width and leaf thickness scale with it, and leaf thickness is the number that actually matters for load — a thin 100 mm leaf and a heavy 100 mm leaf are not the same hinge.
| Size | Typical application |
|---|---|
| 50 – 65 mm | Cabinet doors, small access panels, boxes |
| 75 mm | Light joinery, wardrobe and cupboard doors |
| 85 mm | Light internal doors and heavier cabinetry |
| 100 mm | The standard internal and external door hinge |
| 125 – 150 mm | Heavy, tall or wide doors, and commercial entry doors |
Two quick checks. First, the hinge leaf should not be wider than the door stile will take without the screws breaking out the back. Second, a wide door loads a hinge harder than a tall one of the same weight — width is leverage. If a door is unusually wide for its height, step up a size or add a hinge rather than assuming the height table covers it.
A door closer is the tell. A closer applies force to the door on every single cycle, in both directions, and it does that thousands of times a year. If there is a closer on the door, put ball bearing hinges under it.
A correctly specified hinge fixed with the wrong screws will still fail. Three things to get right:
Hinges live where doors live, and doors near the coast live in salt air. Zinc-plated steel is an interior finish and will bloom in a Queensland wet season if it is on an external door. For anything exposed, choose stainless — and for anything within sight of the water, choose 316 rather than 304. We cover why in stainless or mild steel in coastal Queensland.
Finish matters for a second reason: hinges are usually the only piece of hardware on a door that you never re-finish. Handles get replaced, hinges get painted over badly. Choose the finish that matches the rest of the schedule at the start — matt black, antique, zinc or PVD — and buy the whole job in one batch so the plating comes from one production run.
Our hinge program runs to 33 groups and 418 coded lines, including tower bolts, magnets, latches, brackets, channels and kitchen fittings. Browse hinges and fittings, or take the hinge catalogue and its full size and pack-quantity tables to site.