Concealed Hinges — The Complete Guide

A hinge, known precisely in modern cabinet making as a concealed cup hinge, is a mechanical joint that provides the movable connection between a cabinet door and the carcass. It bears the weight of the door, defines the opening angle, and allows precise alignment of the reveal gap using integrated adjustment mechanisms.

The cup hinge acts like the shoulder joint of the cabinet: it supports the load and defines the exact radius of movement of the door. Unlike traditional surface-mounted hinges, a cup hinge is mounted concealed on the inside. It consists of two main components: the hinge arm with the namesake cup embedded into the door, and the cruciform mounting plate (often simply called the base plate) fixed to the interior of the cabinet side.

This guide provides the technical foundation for selecting, calculating, and installing furniture hinges — from the correct overlay type and opening angles to three-dimensional fine adjustment.

The Three Fundamental Overlay Types

Choosing the right concealed hinges / cabinet hinges depends primarily on the construction of the furniture unit. The overlay type defines how the closed cabinet door is positioned relative to the side panel (carcass side). Mixing up these types inevitably leads to doors that will not close or end up jamming.

1. Full Overlay

With a full overlay, the closed door sits almost completely in front of the front edge of the carcass side. Viewed from the front, the side panel of the cabinet is concealed by the door. Only a minimal gap (the reveal) of approximately 1.5 mm to 2 mm remains towards the outer edge, ensuring the door does not rub against an adjacent cabinet when opened. This variation is the standard for standalone individual cabinets or the outer doors of a cabinet run. The hinge arm of a full overlay hinge is typically straight (uncranked).

2. Half Overlay (Twin Overlay)

A half overlay is used when two doors meet on a single, centrally positioned carcass partition (centre panel). Because both doors must share the front edge of the typically 16 mm or 19 mm thick partition, each door can only cover half of it. A central reveal gap is formed between the two doors. The hinge arm in this variation is slightly bent (half-cranked) to geometrically compensate for the altered pivot point.

3. Inset

With an inset door, the door does not rest on top of the carcass side; instead, it closes flush between the side panels (and usually between the top and bottom panels as well). The front edges of the carcass remain fully visible when the door is closed. This design requires precise calculation of the gaps around the door, otherwise it will bind within the carcass. The hinge for an inset application features a strongly bent (fully cranked) hinge arm.

Opening Angle: The Geometry of Movement

The opening angle determines how far a door can swing open. The choice depends on the room layout, accessibility requirements, and the internal drawers of the cabinet.

Standard Angles for Classic Fronts

For standard wardrobes, kitchen units, or living room cabinets, an opening angle around the 100-degree mark is the industry standard.

• 110° Standard: Concealed hinges / cabinet hinges 110 degrees are the universal solution for nearly all straight cabinet constructions. They provide sufficient clearance to stock shelves or remove clothing.

Wide-Angle Hinges for Maximum Access

When cabinets are fitted with internal drawers (inner pull-outs), a standard opening angle is often insufficient. The open door protrudes into the clear cabinet opening and obstructs the extension of the drawer.

• 155° Zero Protrusion: Concealed hinges / cabinet hinges 155 degrees swing the door far enough outwards that it moves completely clear of the internal carcass space (clear opening). This is mandatory if drawers need to be pulled out from behind the door.
• 165° Wide Angle: Concealed hinges / cabinet hinges 165 degrees offer the maximum opening radius. They are frequently installed in corner cabinets or in units where unobstructed, extra-wide access is essential.

Speciality Angles for Corner Cabinets and Mitres

In kitchen corner units or furniture with angled fronts, the carcass geometry deviates from a standard 90-degree angle. Speciality hinges are used here:

• 30° and 45° Angled Hinges: When the cabinet front is angled, hinges that compensate for this angle are required. Concealed hinges / cabinet hinges 30 degrees and concealed hinges / cabinet hinges 45 degrees are engineered specifically for these asymmetrical mounting situations.
• 90° Blind Corner Hinges: Concealed hinges / cabinet hinges 90 degrees are used when a door is fixed to a stationary filler panel (blind panel) on the same plane. The door does not mount to a deep side wall, but rather to a frontal rail or panel.
• 135° Bi-Fold Doors: For corner cabinets with two-part folding doors (commonly in kitchen corner carousel units), concealed hinges / cabinet hinges 135 degrees are used to flexibly connect the two door panels together.

Closing Mechanisms: Soft-Close vs. Push-to-Open

The way a door closes or opens is determined by the mechanism inside the hinge arm. There are two fundamentally different, technically opposing systems that must never be confused or combined.

Soft-Close (Integrated Damping)

Concealed hinges / cabinet hinges with soft-close feature a small hydraulic or pneumatic cylinder inside the hinge arm or cup. The closing spring pulls the door shut over the final few centimetres, while the damper cushions the movement. The result is a silent, gentle closing action.

• Important: Soft-close hinges actively pull the door shut. They require a handle or pull on the outside of the door.

Push-to-Open (Handleless Fronts)

For handleless furniture, hinges without an automatic closing spring (unsprung) or with a specialised opening spring are required. These work alongside a separate push catch (tip-on mechanism) mounted inside the carcass. When the door is pressed, the catch releases and pushes the door slightly open.

• Technical Error: A soft-close hinge must never be combined with a push-to-open catch. The damper would counteract the push force of the catch, preventing the door from opening.

Selection Criteria and Technical Dimensions

Before installation, the physical characteristics of the cabinet door must be analysed to determine the correct number and size of hinges.

Cup Diameter

The hole drilled into the door to accommodate the hinge cup has standardised dimensions:

• 35 mm: The absolute industry standard for almost all standard furniture doors from 15 mm to 22 mm thickness.
• 26 mm: A smaller diameter for particularly lightweight, narrow, or thin doors (e.g. bathroom furniture or display cabinets).

Number of Hinges per Door

The number of cup hinges required depends on the height and weight of the door. Undersizing leads to door sag and premature wear on the fittings. Recommended guide values for standard MDF or chipboard doors (19 mm thickness):

• Up to 900 mm height / up to 4-6 kg: 2 hinges
• Up to 1600 mm height / up to 12-17 kg: 3 hinges
• Up to 2000 mm height / up to 17-22 kg: 4 hinges
• Up to 2400 mm height / up to 22-26 kg: 5 hinges

Note: The distance between the hinges should be kept as large as possible to distribute leverage forces optimally.

Installation and 3D Adjustment

Installing cup hinges demands precision. When preparing the door, using a Forstner bit (typically 35 mm) together with a drill stand or router is strongly recommended to ensure an accurate, vertical flat-bottomed hole.

Tools Required

• Forstner bit (35 mm or 26 mm)
• Cordless drill/driver
• PZ2 screwdriver (Pozidriv) for adjustment
• Rule and square
• Wood screws (usually Ø 3.5 mm x 16 mm countersunk) or Euro screws for System 32

Drilling and Installation Dimensions

The most critical measurement during preparation is the cup drilling distance (C-dimension). It describes the distance from the edge of the cup hole to the outer edge of the door. This dimension varies depending on the hinge type and manufacturer, but typically lies between 3 mm and 6 mm. Together with the height of the mounting plate, the C-dimension determines the resulting reveal gap.

The cruciform mounting plate is usually fixed in the carcass using System 32. This means the pilot holes are spaced 32 mm apart vertically and set 37 mm back from the front edge of the carcass.

3D Fine Adjustment

Modern clip-on hinges enable tool-free attachment of the door to the carcass (clip technology) and provide three adjustment screws on the hinge arm to align the gaps perfectly after assembly:

1. Depth Adjustment: Moves the door closer to or further away from the carcass. Essential for adjusting the pressure on the soft-close damper or setting the gap between the door and carcass side (1.5 mm to 2 mm).
2. Height Adjustment: Raises or lowers the door. This adjustment is usually achieved by loosening the fixing screws on the mounting plate, which often features elongated slotted holes (adjustment range approx. ± 2 mm).
3. Lateral Adjustment (Side/Overlay Adjustment): Moves the door left or right. This screw regulates the gap between two doors or towards the outer edge. Turning the screw in moves the door edge across the carcass side; turning it out increases the reveal gap.

Common Planning and Installation Errors

Even with high-grade hardware, planning mistakes can compromise functionality.

• Incorrect Screws: Using countersunk screws on mounting plates designed for pan-head screws causes tension and misalignment. When Euro screws (5 mm diameter) are specified, standard wood screws (3.5 mm) must not be used.
• Ignoring Drilling Depth: The cup hole is typically 11.5 mm to 13 mm deep. On thin doors (e.g. 16 mm), there is a risk that the centre point of the Forstner bit punches through the front face of the door. A depth stop is strictly necessary here.
• Clashing with Internal Drawers: If the opening angle or door protrusion (the portion of the door extending into the cabinet opening when open) is not accounted for, pull-out drawers will collide with the hinge edge or the inside face of the door.

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FAQ — Frequently Asked Questions About Hinges

How many concealed hinges do I need per door? That depends on the height and weight of the door. A standard cabinet door up to 900 mm in height requires 2 hinges. Up to 1600 mm requires 3 hinges, up to 2000 mm needs 4 hinges, and tall fronts up to 2400 mm require 5 hinges.

What is the difference between full overlay and inset? With a full overlay, the door sits over the front of the carcass side panels, covering them. With an inset installation, the door sits inside the carcass frame between the side panels, leaving the front edges of the cabinet fully visible from the front.

What is the standard diameter for a hinge cup hole? The standard industry and trade dimension for furniture hinges is a 35 mm cup diameter. For very small or slender doors, specialised hinges with a 26 mm diameter are available.

Can I combine soft-close hinges with push-to-open catches? No. These are two opposing mechanical systems. Soft-close pulls the door shut and holds it closed, whereas a push-to-open catch requires a door that yields under pressure and then springs open. For push-to-open setups, hinges without damping and without closing springs must be used.

When do I need a 155-degree hinge? A 155° or 165° hinge (wide-angle hinge) is strictly necessary if the cabinet contains internal drawers. Due to the wide opening angle, the door swings entirely clear of the internal carcass width (zero protrusion), preventing internal drawers from catching on the door when extended.

How do I adjust a misaligned cabinet hinge? Every modern concealed hinge features screws for 3D adjustment. If the door hangs out of square, use the front screw on the hinge arm (lateral adjustment). Adjusting the screw on the top hinge shifts the top corner of the door left or right until it is level.

What does "System 32" mean for mounting plates? System 32 is an international standard in cabinet construction. It dictates that drilling hole patterns for shelf supports and mounting plates are spaced in a 32 mm grid. The distance from the front edge of the carcass to the first row of holes is standardised at 37 mm.

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Related Categories & Further Guides

To complete your furniture installation, hinge knowledge alone is often not enough. The front mechanics must work harmoniously with the rest of the interior fittings.

• Drawer Runners & Slides: If you are planning internal drawers requiring wide-angle hinges, consult our guide on full-extension and undermount runners to find the correct load capacity ratings.
• Furniture Connectors & Screws: The solid foundation for every carcass. Discover how cam and dowel connectors and chipboard screws with PZ or TX drives are correctly positioned using System 32.
• Flap Fittings & Gas Struts: For upward-opening wall units (e.g. in kitchens), traditional cup hinges are replaced by gas struts, whose force in Newtons (N) must match the flap weight precisely.