How much clearance do I need for ball bearing drawer slides?

Ball bearing slides typically require 12.7mm (1/2 inch) clearance on each side. So the drawer box width should be 25.4mm narrower than the cabinet opening. Always check the manufacturer specifications as some slides may differ slightly.

What is the difference between ball bearing and euro slides?

Ball bearing slides use steel ball bearings for smooth, full-extension movement and can support heavier loads (typically 35-45 kg). Euro or roller slides use nylon rollers, are cheaper, and usually offer 3/4 extension only. Ball bearing slides are preferred for kitchen drawers and heavy-duty use.

How do I choose the right slide length?

The slide must be shorter than the cabinet depth, allowing roughly 25mm rear clearance behind the drawer. Slides come in standard lengths at 50mm increments (250mm to 600mm), so this calculator rounds down to the largest standard length that fits, and sizes the drawer box depth to match that slide so the box never overhangs the runner.

Do undermount slides need side clearance?

Undermount slides (like Blum Tandem) mount underneath the drawer and do not require side clearance. The drawer box width should be 42mm less than the cabinet opening for Blum Tandem slides. Always refer to the manufacturer fitting guide for exact dimensions.

WoodCalcs

Drawer Slide Calculator — Drawer & Slide Dimensions

Work out drawer box dimensions and slide length based on your cabinet opening and slide type.

Slide TypeSets the side clearance: ball-bearing 12.7mm & euro 12.5mm per side; undermount mounts below (box 42mm narrower); wooden 1.5mm per side

Cabinet Opening Width

Internal width of cabinet opening

Cabinet Depth

Internal depth of cabinet

Material Thickness

Drawer box side thickness

Drawer Front Overlap

Overlap on each side of opening

How We Calculate This

This calculator determines the correct drawer box dimensions based on your cabinet opening and chosen slide type.

The formula

Drawer box width = Cabinet opening - (2 x slide clearance) for side-mount slides, or Cabinet opening - 42mm for Blum-style undermount runners.

Slide length = nearest 50mm increment below (cabinet depth - rear clearance), so the runner fits the cabinet.

Drawer depth = slide length, so the drawer box never overhangs the runner you order.

Standard side clearances: Ball bearing 12.7mm per side (25.4mm total), Euro 12.5mm per side, Wooden runners 1.5mm per side. Undermount slides take no side clearance but the box is built 42mm narrower than the opening to sit on the runners below.

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates. Always verify measurements and material quantities before cutting or purchasing.