Full Overlay vs Half Overlay vs Inset Hinges
A full overlay hinge covers the cabinet side entirely, a half overlay hinge shares a central partition with a second door, and an inset hinge sits the door flush inside the cabinet carcass.
Choosing the correct concealed hinge is vital for both the functionality and appearance of furniture. Anyone designing, repairing, or modifying cabinets will inevitably encounter the question of which mounting type is required. The decision depends entirely on the construction of the cabinet carcass and the position of the door relative to the side panel.
Think of the cabinet side panel like a parking space: with a full overlay, one door uses the entire space; with a half overlay, two doors share the surface; and with an inset door, it parks completely inside the garage so the outer walls remain visible. In this technical guide, we examine the differences, hinge arm geometry, and the correct application of these three common hinge types.
The Basics: How Concealed Hinges Work
A concealed hinge (often referred to as a cup hinge) consists primarily of two components: the hinge arm attached to the carcass, and the hinge cup recessed into the door. The standard drilling diameter for the cup is usually 35 mm, or occasionally 26 mm for smaller furniture doors.
The key factor distinguishing the hinge types from one another is the hinge crank. This refers to the bend or offset of the hinge arm. The degree of this bend changes the final resting position of the closed door.
What Is a Full Overlay Hinge?
The full overlay hinge is the most frequently used option in standard furniture construction. When closed, the cabinet door sits over the front edge of the carcass side. The side wall of the cabinet is almost completely concealed by the door.
Technically, the door requires a minimal gap (or reveal) at the edge so that it does not rub against an adjacent cabinet or wall when opening. The hinge arm for this application is straight, meaning it has no or minimal crank (usually 0 mm).
This variant is chosen whenever a standalone cabinet with separate left and right external sides is built. Fitters use full overlay concealed hinges for these standard applications. Typical opening angles for these hinges are 95° or 110°.
What Is a Half Overlay (Twin) Hinge?
A half overlay hinge is used when two doors must be mounted onto a single carcass panel (a centre partition). This is typical for continuous wardrobes, lockers, or large runs of kitchen base units.
Because the front edge of the centre partition is usually only 16 mm or 19 mm thick, both doors cannot fully overlay the edge. Each door may only cover roughly half of the edge width, leaving an adequate gap in the centre so both doors can open without colliding.
To achieve this position, the hinge arm on these fittings is slightly curved. Specialists refer to this as a medium crank (often around 9.5 mm). When planning a wardrobe run with shared dividing panels, half overlay concealed hinges are essential to ensure the twin doors operate cleanly.
What Is an Inset Hinge?
With an inset hinge, the cabinet door does not sit on top of the carcass edges. Instead, it sits flush between the side panels, base, and top of the unit. The front edges of the carcass remain entirely visible when the door is closed.
This design is frequently chosen for aesthetic reasons, such as display cabinets, modern designer furniture, or traditional cabinetry. Technically, this is the most demanding variant. The hinge arm must feature a pronounced bend to swing the door clear of the carcass interior edge during opening. This is known as a high crank (usually 16 mm).
In addition, the position of the mounting plate must be adjusted during installation. It must be set back by the thickness of the door plus the desired gap. Inset concealed hinges are strictly required for these specific builds.
The Differences in Detail
To avoid purchasing errors and incorrect drillings, the differences between the three types can be clearly defined by the following technical characteristics:
- Hinge Arm Geometry (Crank):
- Full overlay: Straight arm (0 mm crank).
- Half overlay: Slightly curved arm (~ 9.5 mm crank).
- Inset: Heavily curved arm (~ 16 mm crank).
- Visibility of the Carcass Side:
- Full overlay: The front edge of the side panel is concealed.
- Half overlay: The front edge of the centre partition is half-covered.
- Inset: The front edge of the side panel is completely visible.
- Mounting Plate Position:
- Full overlay and half overlay: The plate is usually installed according to the standard System 32 dimension (often 37 mm from the front edge).
- Inset: The plate must be set back by the door thickness (e.g. 37 mm + 19 mm door thickness + 2 mm gap = 58 mm).
Which Concealed Hinge Should You Choose?
The decision should be made during the planning phase of the furniture.
Are you planning a freestanding bathroom cabinet, a single chest of drawers, or a standard kitchen base unit? In this case, an overlay door is standard. It conceals the raw edges of the chipboard and creates a clean front. Here, you should use full overlay concealed hinges.
Are you building a continuous wardrobe unit where a wide carcass is divided by vertical partitions with doors hung on both the left and right? Here, you must share the space on the front edge. You will need half overlay concealed hinges.
Should the cabinet feature an exposed outer frame with thicker side panels, allowing the doors to sit elegantly within the carcass? Or are you building a solid wood cabinet whose attractive front edges should remain visible? Then design inset doors and use inset concealed hinges.
Interaction with the Mounting Plate
Regardless of the hinge overlay type, the concealed hinge clips or screws onto a cruciform mounting plate (or linear mounting plate). These plates are available in various heights (e.g. 0 mm, 3 mm, 5 mm).
The height of the mounting plate influences the final overlay of the door. If the door is slightly misaligned after installation or the gap is too large, it can be adjusted using the adjustment screws on the hinge arm. Modern hinges offer 3D adjustment:
- Depth adjustment (gap between door and carcass)
- Lateral adjustment (door overlay across the edge)
- Height adjustment (vertical alignment via the mounting plate)
Special Cases and Opening Angles
Alongside the overlay type, the opening angle is crucial. A standard hinge typically opens to 110°. However, if internal drawers with full-extension runners need to slide past the open door, this angle is insufficient, as the open door will block the runner.
In such situations (often found in kitchen larder units), wide-angle hinges opening to 155° or 165° are used. These swing the door clear of the internal opening width, allowing internal pull-outs to pass freely. These wide-angle hinges are also available in full overlay, half overlay, and inset configurations.
Frequently Asked Questions (FAQ)
Can I use a full overlay hinge for an inset door? No. The kinematics and arm crank are entirely different. A full overlay hinge would immediately force an inset door against the carcass side upon opening, jamming it. For inset doors, an inset hinge must be used.
What does the 35 mm dimension mean for concealed hinges? This is the standard diameter of the cup hole drilled into the furniture door using a Forstner bit. Less commonly, mini hinges with a 26 mm diameter are also available.
How do I calculate the gap for a half overlay setup? If the central partition is 19 mm thick and you mount two doors, each door requires an overlay of approx. 8 mm. This totals 16 mm. The remaining 3 mm forms the reveal between the two closed doors. This gap is necessary to ensure the doors do not rub together when opened simultaneously.
Do all concealed hinges feature integrated damping? No. Many modern hinges have a soft-close mechanism (damper) integrated directly into the hinge cup to prevent doors from slamming shut. However, unsprung or standard sprung versions without dampers are also available, often used in conjunction with push-to-open mechanisms for handleless fronts, as soft-close and push-to-open can mechanically conflict.