Door Hinges Explained: Sizes, Types and How to Choose the Right Ones

Hinges rarely get a second thought until a door starts to sag, squeak, or swing shut on its own. But on a renovation or new build, hinges are also one of the last hardware decisions homeowners make properly — and one of the easiest to get wrong on sizing. This guide covers standard hinge sizes, how many a door actually needs, and how to match them to the rest of your hardware.

What a Hinge Is Actually Doing

A hinge carries the full weight of a door, every time it opens, for the life of the building. Undersized or too few hinges show up over time as a door that drops at the latch side, a gap that widens at the top, or a handle that no longer lines up with the strike plate. Getting the size and quantity right at installation avoids all three.

Standard Door Hinge Sizes

Hinge size is given as height x width, measured across the open leaf. The sizes you'll come across most often on Australian doors are:

• 75mm x 75mm (3" x 3") — lightweight internal doors, including hollow-core and some cabinetry-adjacent applications.
• 100mm x 75mm (4" x 3") — the standard for most internal doors, including solid-core and standard timber doors up to around 40kg.
• 100mm x 88mm (4" x 3.5") — a step up in width, used where a heavier internal door needs more bearing surface without moving to a full 100mm x 100mm hinge.
• 100mm x 100mm (4" x 4") — the standard for external and entry doors, particularly solid timber doors, where a wider hinge better supports both the weight and the additional wind and slam loading an entry door sees.

Thickness matters too: most residential doors are 35mm or 40mm thick, and hinge width should generally not exceed roughly half the door's thickness when fully open, or the door will bind against the frame.

Butt Hinges, Ball-Bearing Hinges and When Each Applies

A plain butt hinge — two flat leaves joined by a pin — is the standard choice for most internal doors and performs well for the lifespan of the door. A ball-bearing butt hinge adds a bearing between the knuckles, which reduces friction and wear under repeated opening and closing. They're worth specifying on heavier doors (solid timber, oversized pantry or laundry doors), high-traffic doors such as a main entry, and any door fitted with a door closer, since closers put continuous load on the hinge.

How Many Hinges Does a Door Need?

Two hinges is the standard for a lightweight internal door up to around 2040mm tall and 40kg. Beyond that, add a third hinge, positioned roughly in the centre of the door leaf:

• Solid-core or solid timber internal doors — three hinges, to spread the additional weight and reduce long-term sag at the latch side.
• Doors taller than standard (2040mm+) — three hinges regardless of weight, since the longer leaf increases leverage on the top and bottom hinge.
• Entry and heavy external doors — three to four hinges is common, especially on solid timber doors 40mm or thicker.

If you're replacing hinges on an existing door rather than speccing a new one, match the existing hinge count unless the door is currently sagging — in which case adding a third hinge is a straightforward fix alongside the replacement.

Measuring for Replacement Hinges

Before ordering, take four measurements from the hinge you're replacing (or the door and frame, if it's a new install):

1. Height and width of the hinge leaf, closed.
2. Knuckle length — the barrel the pin runs through — since this affects how far the door swings clear of the frame.
3. Screw hole spacing, so the new hinge sits over the existing mortise without you needing to re-chisel the frame.
4. Door thickness, to confirm the hinge width will clear when the door is fully open.

Screws are typically a No.8 or No.10 gauge, 25mm–38mm long for internal doors; entry doors and ball-bearing hinges often call for longer screws to reach solid timber in the frame rather than just the jamb lining.

Matching Hinges to Your Handles

Hinges are visible every time a door is open, so it's worth finishing them to match the lever, knob or pull on the same door rather than leaving them in a default finish. Our solid brass hinges are made in the same finish families as our handles — Brushed Brass, Antique Brass and Aged Brass at the warmer end, Black at the darker end, and Nickel, Polished Nickel or Aged Nickel for a cooler palette. Keeping hinges, levers and any cabinet hardware in the same finish family across a room (or a whole house) reads as considered rather than assembled from whatever was on hand.

Buying Guide: What to Specify

When you're ready to order, you'll need: hinge size (matched to door weight and height), quantity per door (two or three, occasionally four), hinge type (standard or ball-bearing), and finish. For a full house or multi-door project, it's worth listing door-by-door rather than ordering one hinge spec for everything — a pantry door and a solid entry door rarely need the same hardware. As with our other solid brass hardware, hinges are made to order, so lead time is worth factoring into your build or renovation schedule alongside the rest of your door hardware.