Drawer hardware planning
Quick answer
Measure the clear cabinet depth, clear opening width and height, drawer material thickness, bottom position, and every obstruction before selecting an undermount slide. Then use the chosen slide model’s installation sheet to determine drawer-width deduction, drawer length, bottom recess, rear notch or boring, and locking-device location.
Nominal slide length alone is not enough. Two 18-inch undermount systems can require different drawer preparation. A dimension published for Blum, Salice, Grass or another brand is not automatically valid for a Berta slide.
The six measurements to record
Use the drawer-box plywood thickness and slide-compatibility chart before choosing the material, and compare the drawer-slide length selection guide before committing to a nominal runner size.
Measurement worksheet
| Item | What to measure | Record | Why it matters |
|---|---|---|---|
| Opening width | Smallest clear width at front, middle and rear | _____ in / mm | Starting value for the model-specific drawer-width deduction |
| Usable depth | Front reference to rear obstruction | _____ in / mm | Limits runner length and bracket space |
| Opening height | Smallest clear vertical opening | _____ in / mm | Controls drawer height and front overlay/inset plan |
| Face-frame setback | Frame projection into cabinet | _____ in / mm | May require spacers or rear mounting support |
| Side thickness | Actual drawer-side thickness | _____ in / mm | Must fall within the selected slide’s limits |
| Bottom thickness | Actual drawer-bottom thickness | _____ in / mm | Affects groove, recess and locking-device preparation |
| Rear conditions | Back, nailers, plumbing, cables, shelf pins | Notes/photo | Prevents choosing a runner that cannot mount or clear |
Use variables until the exact model is confirmed
Drawer outside width = clear opening width − DD is the deduction published for the exact undermount system.
Do not substitute a familiar deduction from another brand. The same rule applies to drawer length, bottom recess, rear notch, fixing holes and locking-device position. A third-party manufacturer’s worksheet is useful for understanding the planning process, but its numbers remain specific to that manufacturer and model.
Choose the runner length from usable depth
| Current Berta nominal length | Use only when | Check before ordering | Do not assume |
|---|---|---|---|
| 12 inches | The measured usable depth and model instructions allow the runner, brackets and drawer preparation | Rear obstruction and drawer-side length rule | That a 12-inch cabinet opening automatically fits |
| 15 inches | The cabinet has sufficient clear depth at both sides | Face-frame setback and rear support | That nominal length equals finished drawer length |
| 18 inches | The complete installed system clears the back and any services | Drawer bottom recess and notch details | That another brand’s 18-inch drilling pattern applies |
| 21 inches | The cabinet depth and drawer front plan leave the required installation space | Runner mounting plane and rear-bracket position | That every standard base cabinet accepts a 21-inch runner |
For the distinction between mounting styles, review the full-extension undermount slide overview and the soft-close slide replacement checklist.
Face-frame and frameless measuring differences
Frameless cabinet
The cabinet sides usually provide continuous mounting planes. Still check that both sides are parallel and that shelf-pin rows, fasteners or a proud back do not interfere.
Face-frame cabinet
The opening may be narrower than the interior box. Record the frame projection and plan blocking or the supplied rear brackets so both runners stay parallel.
Inset drawer front
Front thickness and reveal change the front reference. Do not measure from the door or face frame without defining where the runner starts.
Browse the drawer-slide collection by mounting style, compare the wider cabinet-hardware assortment, and review the current cabinet collection when the drawer system is part of a complete cabinet layout.
Five measurement mistakes that cause expensive rework
- Measuring only at the front. A cabinet that narrows at the rear can bind a precisely built drawer.
- Choosing length from cabinet depth alone. Backs, nailers, brackets and front references reduce usable depth.
- Cutting from a generic online formula. Width deductions and rear preparation are system-specific.
- Ignoring actual material thickness. Nominal plywood thickness can differ from the machined dimension the hardware needs.
- Building all drawer boxes before testing one. Make and install a prototype drawer, verify travel and alignment, then release the batch.
If the project needs help resolving an unpublished installation dimension, use Berta Store’s product-support contact page. The cabinet FAQ and cabinet hardware comparison resources provide additional planning context.
Related hardware and material
Products to verify against the worksheet
Undermount soft-close drawer slides
The current Berta 10-pair kit is offered in 12-, 15-, 18- and 21-inch lengths and lists slides, locking devices, rear brackets and screws. Match the selected length to the measured cabinet, then obtain the exact preparation dimensions before cutting drawer parts.
Review the current undermount kit
1/2-inch BB/BB Baltic Birch
The current 12 mm, 48 × 96-inch option is an unfinished solid-birch panel. It can serve drawer parts only when the selected slide accepts the measured side and bottom construction. The material does not determine the runner clearances.
Check the 1/2-inch Baltic Birch optionFrequently asked questions
How much narrower should the drawer be than the cabinet opening?
Use the deduction published for the exact slide model. Do not assume the side-mount convention or copy a dimension from another undermount brand.
Is drawer length the same as slide length?
Not always. Some systems use a model-specific relationship between nominal runner length and finished drawer length. Confirm that relationship before cutting.
Can I measure an existing drawer and buy the same length?
It is a useful clue, not proof of compatibility. Identify the existing slide, cabinet mounting conditions, drawer preparation and clearances. Replacement hardware may use a different pattern.
Do face-frame cabinets need rear brackets?
Many installations use rear support or blocking, but the correct method depends on the slide and cabinet. The current Berta kit lists rear brackets; confirm their exact placement and the front mounting reference.
Should I build one test drawer?
Yes for a production run. A prototype verifies the width deduction, bottom location, rear preparation, locking devices, reveal and closing action before errors are repeated.
Sources and scope
Berta product details in this article were checked against the current Shopify product record at draft time. For an example of why undermount measurements are model-specific, see Blum’s official TANDEM installation resources. Blum dimensions are third-party manufacturer guidance and are not assigned to Berta hardware.
The correct sequence is simple: measure the cabinet, select the exact hardware, obtain that model’s instructions, calculate the drawer, build one test box, then release production.
