Full-Extension vs Single-Extension Runners: Which Drawer Runner to Choose?

August 9, 2026

A full-extension runner allows a drawer to be pulled 100% out of the carcass, whereas a single-extension runner stops at around 75%, leaving the rear section inside the cabinet.

Choosing the right drawer runner is one of the key technical decisions in furniture making and cabinet repair. Whether in a kitchen unit, a workshop trolley, or a delicate bedside table, the extension type significantly determines ergonomics, storage accessibility, and the maximum load capacity of the construction. Fitters and keen DIY enthusiasts regularly face the question of which runner system is the right choice for their project. This technical guide explores the mechanical differences, load ratings, and specific application scenarios for both systems.

Introduction: When Does the Decision Need to Be Made?

When planning a cabinet carcass or replacing damaged fittings, the runner type must be decided early on. The choice between the two fundamental systems influences not only user convenience, but also the construction of the drawer box itself. Different runners require specific installation clearances at the sides or beneath the drawer bottom. Retrofitting or changing runner types is often possible, but it demands careful checking of the nominal lengths and the side clearances between the drawer side and the internal cabinet wall.

What Is a Full-Extension Runner?

A full-extension runner is a multi-part mechanical slide that opens the entire extension length of the drawer. The extension length matches the nominal length of the runner exactly. For instance, if you install a runner with a length of 500 mm, the drawer can be pulled out by precisely 500 mm from the cabinet.

Technically, this is usually achieved via a three-part telescopic construction. The slide consists of a cabinet profile (screwed to the cabinet wall), an intermediate profile, and a drawer profile. The sliding intermediate profile bridges the distance without compromising stability. Ball-bearing systems are commonly used here, as they guarantee smooth running and high stability under maximum leverage.

This design allows unhindered access right to the back corner of the drawer. Especially with deep drawers, this is a decisive factor for usability. When fitting full-extension drawer runners, there is no need to blindly rummage for items at the back of the cabinet.

What Is a Single-Extension Runner?

A single-extension runner (or partial-extension runner) only opens the drawer travel up to a certain percentage—typically between 70% and 80%. This means part of the drawer remains permanently inside the carcass. Much like an iceberg with a portion always hidden below the surface, the rear quarter of the drawer on a single-extension runner has restricted top-down visibility and accessibility.

Mechanically, these runners have a simpler design. They generally consist of only two profiles: a cabinet profile and a drawer profile, lacking an intermediate compensating profile. This design is very frequently found as standard roller runner drawer slides, where plastic rollers run in powder-coated metal profiles. Basic two-piece ball-bearing slides also fall into this category. The reduced travel distance reduces the leverage on the fixing screws when fully opened, which can be advantageous in very basic furniture made from thin chipboard.

Technical Differences in Detail

To choose the right hardware for furniture construction, compare the technical parameters of both systems.

Travel distance and accessibility: The most obvious difference. Full travel provides 100% access. Single-extension restricts access, requiring items at the back of deep drawers to be lifted out at an angle.
Mechanical complexity: Three-part telescopic slides are more complex to manufacture than two-part roller runners, which is reflected in material use and hardware weight.
Load capacity: Basic single-extension runners with plastic rollers are often designed for dynamic loads of 15 kg to 25 kg. Three-part telescopic runners usually start at 30 kg, and as heavy-duty drawer runners they are available for loads of 45 kg, 80 kg, or even over 100 kg. Load ratings always refer to the total weight (drawer box plus contents).
Mounting position: Both runner types are available for side mounting (on the drawer side) or as undermount drawer runners. With undermount installation, the mechanism is hidden beneath the drawer base, preserving a clean timber look on the sides.
Installation clearance: A standard side-mounted ball-bearing runner generally requires precisely 12.7 mm (1/2 inch) clearance per side. Roller runners often require 12.5 mm. These tolerances must be strictly maintained when cutting the drawer width.

Which Runner Type for Which Application?

The choice depends heavily on the intended use, cabinet depth, and the planned weight of the contents.

Applications for Full-Extension Runners

This type is standard in modern, high-specification furniture making. It is essential when storage depth is generous and heavy or bulky items are stored. In kitchens, full travel is practically mandatory. A 60 cm kitchen cabinet pull-out for pots and pans would be extremely impractical with single-extension runners, as rear pots could not be lifted vertically out of the drawer. For pantry cupboards, workshop units with heavy tools, or office filing cabinets where suspension files must be visible right to the last folder, this is the only technically sound solution.

Applications for Single-Extension Runners

Despite the restricted access, single-extension runners still have their place. They are ideal for shallow furniture. On a bedside table or hallway console with a carcass depth of just 30 cm, losing 25% of the travel is hardly noticeable. Here, short runners such as 250 mm drawer runners or 300 mm drawer runners are entirely sufficient. For light loads like sock drawers or stationery, the simple mechanism performs reliably. They are also more forgiving of minor out-of-square inaccuracies in the carcass.

Additional Features: Soft-Close, Push-to-Open, and Self-Closing

Regardless of extension length, modern runners can feature extra mechanical comfort functions. Precise terminology is important here, as these features are often confused.

Soft-close (damping): An integrated hydraulic or pneumatic damper catches the drawer in the final centimetres of closing and pulls it shut silently and smoothly. Soft-close drawer runners prevent the drawer front from slamming against the carcass and protect the materials.
Push-to-open (tip-on): The mechanical counterpart to soft-close. A spring mechanism is tensioned upon closing. A gentle press on the handleless drawer front releases the spring, pushing the drawer open by a few centimetres. Push-to-open drawer runners enable minimalist, handleless furniture design. Important: A purely mechanical slide cannot feature both soft-close and push-to-open at the same time, as the mechanisms work in opposite ways (damping slows down, springs push out).
Self-closing: A simpler variant without damping. A spring actively pulls the drawer into the cabinet over the final centimetres, albeit unbraked. Self-closing drawer runners ensure drawers are not accidentally left slightly ajar.

Frequently Asked Questions (FAQ)

Can I replace a single-extension runner with a full-extension runner? Yes, this is generally straightforward provided the side clearance (typically 12.7 mm for ball-bearing runners) matches. Simply measure the existing runner and select a new telescopic slide with the same nominal length. Pay attention to the screw hole patterns, as they may differ slightly, requiring new fixing holes to be drilled in the carcass.

How do I measure the nominal length correctly? The nominal length always refers to the length of the closed runner, which typically corresponds to the outer depth of the drawer box. If your timber drawer box measures 400 mm along the side, you require 400 mm drawer runners. The runner should never be longer than the internal cabinet depth.

Are roller runners always single-extension? In the vast majority of cases, yes. A classic two-part roller runner does not provide full extension. There are occasional specialist roller constructions that extend further, but standard full-extension today is almost exclusively achieved using ball-bearing telescopic slides or modern undermount systems.