Undermount Slide Drawer Box Dimensions: Guide for Blum & Richelieu (with Diagrams)

Cordova Woodworking
May 11
2 min read

When using BLUM or Richelieu undermount slides, your drawer box construction must be precise. Unlike side-mount slides, undermounts require specific clearances to and exact dimensions ensure that smooth, "soft-close" motion.

This guide provides the exact specifications and drawer box diagrams to help you build perfect drawer boxes.

Thickness: Calculating undermount slide drawer box dimensions correctly.

To ensure compatibility with most undermount slides and the locking devices, your material thickness is the most critical starting point.

Material Thickness: The drawer front, sides, and back components must be 5/8" (16mm) thick. Consider using 5/8" (16mm) thick Baltic Birch
Bottom Material: 1/4" (6mm) thick plywood or MDF

1. Drawer Side Length

When calculating your undermount slide drawer box dimensions, add 3mm to the length of the slide to ensure the rear hooking mechanism engages perfectly.

The Formula: Slide Length + 3mm.
Example: If you are using 300mm slides, your drawer sides must be cut to a total length of 303mm.

2. Drawer width

The width of your drawer box is determined by the cabinet opening

The Formula: Cabinet Opening minus 42mm
Example: If your cabinet opening is 400mm, the front and back pieces of your drawer box must be 358mm
- This dimension must be precise!

Technical diagram showing assembled drawer box dimensions for undermount slides, highlighting the 5/8 inch material thickness and total depth and width calculation

Pro Tip: Planning for Inset Drawer Faces

If your design features inset drawer faces (like the video above), you must choose your slide length accordingily.

Select drawer slides that are at least 1" (25mm) shorter than the internal depth of your cabinet. This creates the necessary clearance for the thickness of the drawer face.

Detailed Component Breakdowns

Refer to the diagrams below for dimensioning each drawer box component.

1. Dado for drawer bottom

The drawer bottom panel must be offset to hide the slide hardware underneath.

Offset: Cut your dado 1/2" (13mm) up from the bottom edge of the front, side, and back components.
Why? This 13mm "cavity" underneath the drawer bottom is where the slide sits.

2.rear clearance Notch

You must cut a notch in the back panel of the drawer box to allow clearance for the slides

Dimensions: 1/2" (13mm) tall by 1-1/2" (38mm) wide.
Timing: Cut this notch before assembling the box. It is significantly harder and less safe to cut once the box is built.