MachineCalcs

Drawer Slide Calculator

Size cabinet drawer slide clearances, drawer box width and rounded slide length from a finished opening, cabinet depth, setbacks and hardware allowance.

Materials 12 inputs 12 results
Used in Woodworking 25

Calculator

Inputs

View results
Used for guidance notes only. Enter the exact clearance and prep values from the hardware instructions.
Approximate extension travel relative to nominal slide length.
Finished opening width inside the face frame or cabinet sides.
in
Finished drawer opening height before top and bottom clearance.
in
Usable inside depth from the front reference plane to the back obstruction.
in
Clearance between each drawer side and the cabinet opening. Many side-mount slides use 1/2 in per side.
in
Clearance above the drawer box.
in
Clearance below the drawer box for slide hardware and reveal.
in
Distance from the front reference plane to the slide or drawer box front reference.
in
Clearance for the cabinet back, rear bracket, bumper or obstruction.
in
Catalog rounding increment used to choose a slide length at or below available depth.
in
Used only to estimate inside drawer width after box width is calculated.
in

Results

Default result
Edit inputs
Drawer box width(W_box)
20in
Pass

opening width minus side clearance on both sides

Also computed

Drawer box height(H_box)Pass5in

opening height minus top and bottom clearance

Available slide depth(D_avail)Pass22.375in

cabinet depth minus front setback and rear clearance

Recommended slide length(L_slide)Pass22in

rounded down to the entered slide length increment

Recommended box depth(D_box)22in

uses the rounded slide length as a first-pass box depth

Depth reserve(D_res)Pass0.375in

available slide depth minus selected slide length

Required cabinet depth(D_req)22.625in

selected slide length plus front setback and rear clearance

Drawer slide sizing preview: 20.00 inch box width, 22 inch slideDrawer slide sizing previewOpening clearance sets box width; cabinet depth sets usable slide length.finished openingside clearanceside clearanceslide length22 indepth reserve0.37 inDrawer box outside width20.00 inDrawer box height5.00 inEstimated travel22.00 in
Method notes 4 notes
  • Drawer box width = opening width - 2 x side clearance.
  • Available slide depth = cabinet inside depth - front setback - rear clearance.
  • Recommended slide length is rounded down to the entered catalog increment so the slide fits the available depth.
  • This is a side-mount slides usually need a fixed clearance per side; verify the exact model. It does not replace manufacturer instructions for locking clips, notch dimensions, rear brackets, disconnect clearance, face-frame brackets, drawer-front reveal, load rating, screw pattern or soft-close hardware.

Drawer slide sizing starts from finished opening width and cabinet inside depth. Drawer box width = opening width - 2 x side clearance, and available slide depth = cabinet depth - front setback - rear clearance. This calculator rounds slide length down to the entered catalog increment, then reports box width, box height, depth reserve, required cabinet depth and estimated travel.

Continue workflow

All Materials
Workflow placement Woodworking Stage 2: Build cabinet parts
Next 1 Size drawer box Carry accepted slide clearances into full drawer-box side, front, back and bottom-panel dimensions. Next 2 Size cabinet doors Size drawer fronts or adjacent cabinet doors from the same opening and reveal assumptions. Next 3 Build cut list Turn accepted box and slide dimensions into repeated drawer side, front and back stock cuts. Chart Use reference data Decimal to fraction chart

How to use this calculator

  1. Measure the opening. Enter the finished drawer opening width and height.
  2. Measure cabinet depth. Use inside depth from the front reference plane to the back obstruction.
  3. Set hardware clearances. Enter side clearance, top/bottom clearance, front setback and rear clearance from slide data or shop standards.
  4. Choose slide increment. Use the catalog length increment for the hardware family you plan to buy.
  5. Check the result. Use box width, box height, rounded slide length and depth reserve as a first-pass cabinet layout.

How it works

Drawer slide sizing starts with the measured cabinet opening. Box width subtracts side clearance on both sides: drawer box width = opening width - 2 x side clearance

Usable slide depth subtracts the front setback and rear clearance from the cabinet inside depth: available slide depth = cabinet depth - front setback - rear clearance The calculator rounds that depth down to the entered slide length increment so the selected nominal slide length fits the cabinet.

For adjacent cabinet work, use the drawer box size calculator for a fuller box cut-list screen, the cabinet door size calculator for matching fronts, and the cut list calculator for repeated rails, sides and drawer parts.

Worked example

Verified against the live calculator

A 21 in wide opening with 1/2 in side clearance on each side gives a 20 in drawer box width. With a 23 in cabinet depth, 1/8 in front setback and 1/2 in rear clearance, usable slide depth is 22.375 in. Rounding down to a 2 in slide length increment gives a 22 in slide and 0.375 in of depth reserve.

Frequently asked questions

How do I calculate drawer slide size?

Start with cabinet inside depth, subtract front setback and rear clearance, then round the available depth down to an available slide length. The exact catalog length and installation details still come from the slide manufacturer.

How do I calculate drawer box width for side-mount slides?

Use drawer box width = opening width - 2 x side clearance. Many side-mount slides use 1/2 in per side, but the exact hardware model controls the final clearance.

Does this work for undermount slides?

It can screen opening width, usable depth and slide length if you enter the manufacturer clearance values, but undermount clips, notches, rear holes and drawer-side rules are brand-specific.

Is the slide length the same as drawer depth?

For a first-pass cabinet layout, the calculator uses the rounded slide length as recommended box depth. Some hardware families allow or require different drawer depth, so check the slide sheet before cutting parts.

Method & assumptions

  • Opening dimensions are finished measured dimensions, not nominal cabinet sizes.
  • Side clearance, setbacks and slide length increments are entered values because hardware families vary.
  • Rounded slide length is selected at or below available slide depth.
  • Estimated travel is only a travel-mode screen; soft-close, over-travel and disconnect hardware can change usable motion.
  • Does not solve load rating, screw patterns, rear brackets, face-frame brackets, clips, notches, locking devices, drawer-front reveals, soft-close interference, racking or manufacturer-specific installation details.
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