Drawer Box Calculator for Undermount and Side-Mount Slides

Pick your slide, enter the opening and the actual thickness of your drawer sides, and get a cut list in inches and millimetres.

Your measurements

Measure the cabinet opening and pick your slide. Everything updates as you type.

Slide

Drawer slideInside −42 mm

Inside width = opening − 42 mm (1 21/32"). From Blum's documentation.

Cabinet opening

Opening width

Clear width between the cabinet sides (or face frame), measured at the front.

Common widths

Opening height

Inside cabinet depth

From the back of the face frame (or front edge) to the cabinet back. Used to pick the runner length.

Drawer sides

Nominal side thickness

Measured side thickness

Measure with calipers. Plywood is often thinner than its nominal size, and with this slide the outside width depends on it.

Outside width23 19/32"

Outside width of the drawer box

23 19/32"

= 599.4 mm

Build the box to this width so the Blum TANDEM 563H (for 5/8" / 16 mm sides) runners fit. It is 10.3 mm (13/32") narrower than your opening.

Front and back: 22 11/32"; = 567.6 mm; Between the sides
Max box height: 5 7/32"; = 132.4 mm
Side length: 21"; = 533 mm; Runner needs 557 mm depth
Inside width: 22 11/32"; = 567.6 mm

Shaded: slide space, 3/16" · 5.1 mm each side. Dashed: bottom groove, 1/2" · 13 mm up from the lower edge.

Cut list

Bottom sits in a groove 1/2" (13 mm) up from the lower edge, 6.35 mm deep.

Part	Qty	Length	Width / height
Sides	2	21"533 mm	5 7/32"132.4 mm
Front and back	2	22 11/32"567.6 mm	5 7/32"132.4 mm
Bottom panel	1	20 1/4"514 mm	22 27/32"580.3 mm

How this was calculated

The slide maker's rule, with your numbers.

Step 1: Find the inside drawer width
Inside width = opening width − 42 mm
= 609.6 mm − 42 mm
= 567.6 mm
Blum gives the inside width of the box for this slide, because the runners sit under the drawer and hook into the sides.
Step 2: Add both drawer sides
Outside width = inside width + 2 × side thickness
= 567.6 mm + 2 × 15.88 mm
= 599.4 mm (23 19/32")
With these sides the box ends up 10.3 mm (13/32") narrower than the opening. Thinner or thicker sides change the outside width, so measure them.
Step 3: Cut the front and back
Front/back = outside width − 2 × side thickness
= 599.4 mm − 2 × 15.88 mm
= 567.6 mm (22 11/32")
With butt joints the front and back fit between the sides.
Step 4: Check the height
Max side height = opening height − 20 mm
= 152.4 mm − 20 mm
= 132.4 mm (5 7/32")
The bottom sits 13 mm up from the lower edge of the sides so the runner fits underneath.

Sources

Blum TANDEM 563H (for 5/8" / 16 mm sides): width rule, height allowance and runner lengths
Checked against source
Checked against the maker's documentation. Checked 23 Oct 2026.
- Blum TANDEM plus BLUMOTION 563H installation instructions, opened 23 Oct 2026

In short

Blum TANDEM 563H: Inside width = opening − 42 mm (1 21/32"). A 24" opening with 5/8" sides gives a box 23 19/32" (599.4 mm) wide.

Slides with a maker's sheet use its width rule and clearances.

Drawer slides compared

Undermount slides set the inside width of the box; side-mount slides set the outside width. The last two columns are how much narrower than the opening the outside of the box ends up.

Slide	Width rule	Bottom recess	Opening − box, 5/8" sides	Opening − box, 3/4" sides	Basis
Blum TANDEM 563H (for 5/8" / 16 mm sides)	Inside −42 mm	13 mm	10.3 mm (13/32")	Not for 3/4" sides	Maker's instructions
Blum TANDEM 563F (for 3/4" / 19 mm sides)	Inside −49 mm	13 mm	17.3 mm (11/16")	10.9 mm (7/16")	Maker's instructions
Blum MOVENTO 760H	Inside −42 mm	13 mm	10.3 mm (13/32")	Not for 3/4" sides	Maker's instructions
Salice Futura (full-extension undermount)	Inside −41 mm	12.5 mm	9.3 mm (3/8")	Not for 3/4" sides	Maker's instructions
Generic side-mount ball-bearing slide (1/2" side space)	Outside −25.4 mm	None	25.4 mm (1")	25.4 mm (1")	Typical (estimate)
Accuride 3832E side-mount full extension	Outside −25.4 mm	None	25.4 mm (1")	25.4 mm (1")	Maker's instructions
Grass Dynapro 2.0 (for 5/8" / 16 mm sides)	Inside −42 mm	13 mm	10.3 mm (13/32")	Not for 3/4" sides	Maker's instructions
King Slide push-to-open undermount (model not confirmed)	Inside −42 mm	12.5 mm	10.3 mm (13/32")	Not for 3/4" sides	Typical (estimate)
Hettich Quadro V6 / 4D V6 (IW 21)	Inside −42 mm	12.7 mm	10.3 mm (13/32")	Not for 3/4" sides	Maker's instructions
Heavy-duty side-mount slide (generic)	Outside −38.1 mm	None	38.1 mm (1 1/2")	38.1 mm (1 1/2")	Typical (estimate)

Measure your drawer sides with calipers: plywood sold as 5/8" or 3/4" is often thinner, and with undermount slides every 0.5 mm of side thickness changes the outside width by 1 mm.

Worked example: Blum TANDEM 563H, 24" opening, 5/8" sides

The steps the calculator runs for an undermount slide.

Step 1: Find the inside drawer width
Inside width = opening width − 42 mm
= 609.6 mm − 42 mm
= 567.6 mm
Blum gives the inside width of the box for this slide, because the runners sit under the drawer and hook into the sides.
Step 2: Add both drawer sides
Outside width = inside width + 2 × side thickness
= 567.6 mm + 2 × 15.88 mm
= 599.4 mm (23 19/32")
With these sides the box ends up 10.3 mm (13/32") narrower than the opening. Thinner or thicker sides change the outside width, so measure them.
Step 3: Cut the front and back
Front/back = outside width − 2 × side thickness
= 599.4 mm − 2 × 15.88 mm
= 567.6 mm (22 11/32")
With butt joints the front and back fit between the sides.
Step 4: Check the height
Max side height = opening height − 20 mm
= 152.4 mm − 20 mm
= 132.4 mm (5 7/32")
The bottom sits 13 mm up from the lower edge of the sides so the runner fits underneath.

Drawer boxes: common questions

Width rules, examples and choosing a slide.

How do I calculate drawer box width?

It depends on the slide. Undermount slides give the inside width of the box (opening minus a fixed amount), so add both side thicknesses for the outside width. Side-mount slides give the outside width directly: opening minus the clearance the slides need on both sides.

How wide is a drawer box for a 24" opening with Blum TANDEM 563H slides?

Inside width = opening − 42 mm (1 21/32"). With 5/8" sides the box is 23 19/32" (599.4 mm) wide outside and the front and back are 22 11/32" (567.6 mm) long for butt joints.

Which slide should I pick in the calculator?

The model printed on your slides or their packaging. Slides marked as estimates use typical values; for those, check the instructions that came with the slides before cutting.