Design precise drawer boxes from opening sizes with customizable slide clearances built-in. Get cut lists, inside dimensions, and exportable reports for faster builds always.
Enter the cabinet opening and your preferred construction options. The calculator estimates box sizes, inside space, and a practical cut list.
Outside width = Opening width − 2 × Side clearance.
Outside height = Opening height − Top clearance − Bottom clearance.
Usable depth = Opening depth − Back clearance.
Outside depth = min(Usable depth, Slide length).
Inside width = Outside width − 2 × Side thickness + Joinery allowance.
Bottom panel depends on mounting: captured uses groove depth, on-bottom matches outside size.
| Opening (W×H×D) | Slide length | Side clearance | Outside (W×H×D) | Inside (W×H×D) |
|---|---|---|---|---|
| 18 × 6 × 21 in | 18 in | 0.5 in | 17 × 5.75 × 18 in | 16 × 5.5 × 17 in |
| 24 × 8 × 22 in | 20 in | 0.5 in | 23 × 7.75 × 20 in | 22 × 7.5 × 19 in |
| 400 × 180 × 520 mm | 450 mm | 12.7 mm | 374.6 × 173.7 × 450 mm | 349.2 × 167.3 × 424.6 mm |
Values are illustrative; verify hardware specs before cutting.
Professional guide for drawer box sizing
Measure width at the front and back, and height at both sides. Use the smallest measurement to prevent binding. A difference as small as 1.5 mm (1/16 in) can change fit, especially on wide drawers or face-frame openings.
Side-mount slides commonly need about 12.7 mm (0.500 in) per side, while many undermount systems use tighter side clearances but add bottom and rear requirements. Enter the exact specs for your slide model and keep the clearance consistent across a batch.
A practical starting point is 3.2 mm (0.125 in) top clearance and 3.2 mm (0.125 in) bottom clearance. These gaps protect against seasonal movement, minor racking, and finish build-up. Reduce gaps only when hardware allows it and the cabinet is very square.
Drawer depth is limited by both the slide length and the usable cabinet depth. The calculator uses Outside Depth = min(Open Depth − Back Clearance, Slide Length). A typical back clearance is 6.4 mm (0.250 in) for stops, screws, and installation tolerance.
Common box stock is 12.7 mm (1/2 in) or 15.9 mm (5/8 in). Thicker sides increase stiffness, reduce racking, and support heavier loads, but reduce inside width slightly. For wide drawers, thicker sides often improve long-term performance.
Butt joints are fast and predictable; rabbets and dados add glue surface and alignment. For captured bottoms, groove depth commonly ranges 6.4–9.5 mm (0.250–0.375 in) depending on tooling and panel thickness. The calculator expands bottom size by 2× groove depth so the panel seats properly.
Inside width, height, and depth determine usable volume and organizer compatibility. If you are planning dividers, trays, or file rails, confirm the inside depth after subtracting front/back thickness and the bottom thickness. Always check for hardware intrusions like hinges or corner blocks.
Build one test drawer first. Confirm smooth travel at full extension, verify face reveals or overlay margins, and measure diagonals to ensure the box is square. A 2 mm out-of-square condition can cause rubbing even when the clearances look correct on paper. This approach reduces rework and waste.
1) What side clearance should I use for my slides?
Use the slide manufacturer’s specification. Many side-mount slides use about 0.500 in (12.7 mm) per side. Undermount systems vary, so confirm the exact figure for your model before cutting.
2) Why does the calculator limit drawer depth to slide length?
Slides are designed to support a specific extension length. If the drawer is deeper than the slide, the box may hit the back or bind during travel. Using the smaller of usable depth and slide length improves reliability.
3) How do I choose top and bottom clearances?
Start with 0.125 in (3.2 mm) at the top and bottom, then adjust to match hardware and cabinet quality. Tight clearances demand squarer cabinets and careful finishing to avoid rubbing.
4) What groove depth is typical for a captured bottom?
A common groove depth is 0.250–0.375 in (6.4–9.5 mm), depending on panel thickness and tooling. Ensure the groove leaves enough material for strength and fully supports the bottom panel edges.
5) Can I calculate in millimeters and still export files?
Yes. Select mm as the unit and all results, cut list values, and exports will use millimeters. Keep your inputs consistent, especially clearances, so the output matches your measuring tools and shop standards.
6) What is the difference between inset and overlay face sizing?
Inset sizing subtracts reveals (gaps) from the opening for a flush look. Overlay sizing adds an overlay amount around the opening. The calculator provides an estimate; always confirm hinge, pull, and reveal preferences.
7) How should I handle real-world tolerance and cabinet squareness?
Use the smallest opening dimension, build one test drawer, and verify diagonal measurements. If cabinets are out of square, add clearance or correct the cabinet. Small errors compound on wide or deep drawers.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.