Instructions for how to measure cabinet openings to determine drawer box size and drawer slides.
If you are reusing old drawer slides, you can measure the outside of your existing drawer box. These are the dimensions needed to make a new drawer. If the box you are replacing is missing or hard to measure, you can use a box from a different opening if the opening is the same size.
What size drawers slides do I need?
In order to determine what drawer slide size you need, you must first decide what type of drawer slides you want to use. There are two main styles that we recommend: Side Mount and Under Mount. These terms refer to how the slide mounts to the drawer box. Both mount to the cabinet in similar ways.
For example, when asking: "My cabinet depth is 23 inches, what size slides do I need?" The answer depends on whether you want side mount or under mount slides.
- For undermount slides, you drawer and slides should be 21" in depth.
- For side mount slides, your drawer and slides should be 22" in depth.
Blum Tandem Under Mount Slides
(Images courtesy of Blum Hardware)
Measure the exact width and height of your opening. Also, measure from the face of the cabinet to the back inside wall of the cabinet.
For the new drawer box width:
- If using a drawer box with 1/2" thick sides, subtract 5/8".
- If using a drawer box with 5/8" thick slides, subtract 3/8".
To determine the drawer box height, subtract at least 13/16" from the opening height.
The depth of the new drawer box should match the slide length. Available undermount slide lengths are 9", 12", 15", 18", and 21" in standard duty and 18", 21", 24", 27", and 30" in heavy duty.
Kitchen cabinets will usually use a 21" slide so the drawer box must be exactly 21". Bathroom cabinets usually need 18" slides with 18" deep drawer boxes.
Side Mount Slides
Measure the exact width and height of your opening. Also, measure from the face of the cabinet to the back inside wall of the cabinet.
For the new drawer box width, subtract 1-1/16" from the opening width. This is regardless of drawer box side thickness.
To determine the drawer box height, subtract at least 1/2" from the opening height.
The outside depth dimension of the new drawer should usually match the slide length. Available side mount slide lengths are 10", 12", 14", 16", 18", 20", 22", 24", 26", 28", and 30". For example, a 20" drawer set up for side mount slides should have 20" side mount slides.
When using side mount slides, kitchen cabinets usually need 22" slides and bathrooms usually need 18" slides.
How much clearance space do i need in the rear of a drawer when using a rear mounting bracket?
For a drawer with a rear mounting bracket, the clearance you need depends on the type of slides you will use.
Typically:
- Side mount slides usually need up to 3/8 inch of clearance.
- Under mount slides may require a bit more clearance, often around 1/2 inch to account for the mechanism’s rear stop feature.
The exact requirement can vary depending on the bracket type, drawer slide model, and any additional rear adjustments or stop features. It’s always best to check the specifications provided by the manufacturer of your specific drawer slides, as they sometimes list unique requirements for optimal performance.