What Size Cutout Does a USB Charging Module Need? (OEM Installation Guide)
For a furniture OEM, the cutout is not a detail. Once the CNC program is locked and a hundred desk tops have been routed, there is no going back. A USB charging module that fits beautifully on the spec sheet becomes an expensive rework if the cutout dimension does not match the actual module flange, or if the cavity underneath leaves no room for the wiring.
This guide walks through the practical question every furniture engineer asks: what size cutout does a usb charging module need? It covers standard modular sizes, the hidden dimensions that buyers often forget, and a checklist before CNC machining starts.
Most commercial modules follow a 45 mm modular grid: 22.5 mm, 45 mm, 67.5 mm, or 90 mm wide units.
The cutout dimension is not the module's outer width; it is the inner flange dimension, and it must come from the supplier's drawing.
Depth clearance under the desk, cable routing, and material thickness matter as much as the top-side cutout.
Always ask the supplier for the exact cutout drawing before releasing the CNC program.
A 1-2 mm tolerance around the cutout is the practical rule of thumb for clean installation.
Why the Cutout Is an OEM Decision
A retail charger is dropped into a bag. A USB charging module is built into the furniture. The top-side opening, the underside cavity, the routing of the incoming cable, and the fixing method all have to be planned before production starts. This is why a manufacturer who asks for the cutout drawing at the end of the project is already too late.
Standard Modular Sizes
Most commercial furniture modules are designed around a 45 mm modular grid, shared with many European office furniture systems. The "way" count describes how many 45 mm units the module occupies:
| Module size | Typical face dimension | What it usually holds |
|---|---|---|
| 0.5 Way | 22.5 × 45 mm | A single small charging port or a single USB-A / USB-C outlet |
| 1 Way | 45 × 45 mm | USB-A + USB-C, or a small single-port charger |
| 1.5 Way | 67.5 × 45 mm | Two to three ports, e.g. USB-A + dual USB-C |
| 2 Way | 90 × 45 mm | Multi-port modules, e.g. 2C1A three-port with higher wattage |
The cutout the OEM actually machines is the inner opening under the module flange, not the 45 mm grid itself. The flange overhangs slightly on all sides, so the cutout dimension is smaller than the visible face. Always use the supplier's outline drawing, not a self-measured number.
The Hidden Dimensions Buyers Forget
Depth Clearance Under the Surface
The module does not end at the desk top. The body drops below the surface, and the terminals and cable take additional depth. Before fixing a cutout, confirm the total depth from the underside of the material to the back of the module, and leave room for the incoming cable bend. In thin desktops or under-trunking installations, this is where most installation problems show up.
Material Thickness
The fixing method assumes a certain material thickness range. A clip-on spring clip grips panels in a typical range; outside that range the module either drops through or cannot seat. Confirm the furniture material thickness against the supplier's fixing specification before ordering hardware.
Incoming Cable Routing
A module that fits perfectly on the top side still fails if the incoming cable cannot bend away underneath. Plan the cable route in the same 3D model as the cutout, and check the terminal orientation against the trunking, desk leg, or modesty panel.
Cutout Tolerance
As a practical rule of thumb, a 1-2 mm tolerance around the nominal cutout gives the installer room to align the flange without binding. Tighter tolerances cause binding; looser tolerances show gaps around the flange.
Fixture and Tooling Setup
Once the cutout dimension is confirmed, the next production question is how to repeat it accurately across hundreds of units. A single one-off cut by hand is different from a CNC program that runs a hundred desks in a row. The CNC operator needs a fixture that holds the panel consistently, a bit that matches the corner radius specified on the drawing, and a work offset that places the cutout exactly where the furniture design expects it. A 1 mm error in work offset shifts every unit in the batch, and by the time it is noticed, the batch may already be cut.
It is good practice to cut a test panel first, measure the cutout against the module, and then run a small pilot batch of three to five units before committing to full production. The pilot batch catches both drawing errors and setup errors, and the cost of a five-unit pilot is trivial next to the cost of a hundred-unit rework. This pilot step is where the supplier's installation sample meets the manufacturer's production reality.
It is also worth confirming how the cutout is referenced in the CNC program. Best practice is to reference the cutout from a known datum on the furniture, not from a freehand position, so that every desk in the batch has the module in the same place. A module that moves 10 cm from desk to desk may look like a small issue on paper, but it shows up as inconsistent ergonomics and repeated complaints once the furniture is in daily use.
Cutout Preparation Checklist
| Check item | Why it matters |
|---|---|
| Supplier outline drawing with exact inner cutout dimensions | Avoids machining to a guessed size |
| Total module depth including terminals and cable bend | Prevents collisions under the desk |
| Material thickness range compatible with the fixing method | Ensures a secure clip or screw fit |
| Terminal orientation against cable route | Prevents forced cable bending |
| Cutout tolerance of 1-2 mm | Clean installation, no gaps, no binding |
| Sample fit before full production | Catches drawing mismatches before CNC runs |
Different Materials, Different Cutting Methods
The same module cutout behaves differently depending on what the furniture top is made of. Wood and veneer are forgiving: a CNC router or a simple router jig cuts cleanly, and the material tolerates small edge variations. Compact laminate and solid-surface materials cut cleanly but chip if the tool is dull, so a fresh cutter and a slow feed matter. Glass and stone are a different category altogether: they require diamond tooling, water-cooled cutting, and a slow feed, and they crack if the cutout corner is sharp rather than rounded.
Before the CNC program is locked, the engineer should confirm the material supplier's recommended cutting parameters for that specific material. A cutout that machines perfectly in MDF may fail in 12 mm veneer, and a cutout that works in laminate may require a different corner radius in tempered glass. This is another reason the sample step is non-negotiable: the sample should be cut from the actual production material, not a spare panel of a different species.
Edge finishing also matters. A cutout in wood that will be covered by the module flange needs only basic sanding. A cutout in glass or stone that is not fully covered by the flange needs a polished edge, because a raw cut edge shows. The buyer should decide which edges are visible before cutting, not after.
Replacement and Retrofit Considerations
Not every cutout is cut from new. Many projects retrofit a usb charging module into an existing table, or replace a broken module in a previously installed one. In both cases, the existing cutout size is fixed, and the buyer's choice of new module is constrained by it. This is why suppliers who offer the standard 45 mm grid sizes — 22.5, 45, 67.5, and 90 mm — are easier to retrofit than one-off custom sizes: there is a reasonable chance that a future replacement module fits the existing hole.
When retrofitting, the buyer should also check the existing cavity. A table built ten years ago may have a different underside depth than a modern design, and the new module may not clear the modesty panel or the cable tray. Measuring the available cavity before ordering a replacement avoids the common situation where the new module arrives and physically does not fit.
For long product programs, it is worth recording the exact cutout and module model in the furniture's maintenance documentation. Ten years later, when a module fails, the facility team can order the same replacement without guessing dimensions. This is a small documentation step that saves hours of downtime.
Common Installation Mistakes
| Mistake | Consequence | Fix |
|---|---|---|
| Machining to the visible face size instead of the inner cutout | Module is loose or falls through | Use the supplier's cutout drawing |
| Ignoring underside depth | Module hits the modesty panel or trunking | Plan depth in the 3D model |
| No tolerance around the cutout | Flange binds; cannot seat | Leave 1-2 mm tolerance |
| Reversing terminal orientation | Cable cannot route cleanly | Confirm orientation on the drawing |
| No sample test before full run | All units need rework | Fit one sample in the actual material first |
For EU-facing products, the module itself should still meet the baseline expectations of any commercial usb charging module: safety aligned with IEC 62368-1, relevant EMC compliance, and — where ecodesign rules apply — alignment with Regulation (EU) 2019/1782. The cutout drawing and the certification document should travel together in the OEM's drawing package.
Summary
The right cutout size is not a number to guess. It is the inner opening shown on the supplier's outline drawing, planned together with the underside depth, material thickness, cable route, and CNC setup. For most commercial furniture, the modular grid runs 22.5, 45, 67.5, and 90 mm wide; beyond that, the difference between a clean install and a rework batch is whether the engineer asked for the drawing, planned the fixture, and fitted a sample in the actual material before the CNC program was released. These steps take days, not weeks, and they are the cheapest insurance a furniture OEM can buy against a batch of desks that arrive with the wrong hole.
For the furniture buyer who is not an engineer, the practical takeaway is simple: never rely on a measured number from an installed unit. Every module batch, every supplier revision, and every manufacturing tolerance shifts the cutout by a fraction. The supplier's current outline drawing is the only source of truth, and it should be reconfirmed whenever the module model changes or a new supplier is quoted.
Planning a furniture project with embedded charging?
Glob-el supplies USB charging modules in standard 22.5×45, 45×45, 67.5×45 and 90×45 mm sizes, with full outline drawings, fixing specifications, and sample units available before production. Modules cover USB-C PD from 20 W to 140 W, with CE, CB and VDE alignment and UL94 V-0 housings.
Request a Custom QuoteFAQ
What is the standard cutout size for a USB charging module?
Most commercial modules follow a 45 mm modular grid: 22.5 × 45, 45 × 45, 67.5 × 45, or 90 × 45 mm face sizes. The actual cutout is the inner opening under the flange, taken from the supplier's drawing.
How much depth does a module need under the desk?
It depends on the module and its terminals. Always confirm the total depth from the underside of the material to the back of the module, and leave extra room for the cable bend.
Can I install a module in glass or stone?
Possible, but the cutting method and fixing are different from wood. Confirm the cutting tool, material thickness, and fixing method with the module supplier before choosing the surface material.
What tolerance should I leave in the cutout?
A practical rule of thumb is 1-2 mm around the nominal cutout. Tighter causes binding; looser shows a visible gap around the flange.
Does a higher wattage module need a larger cutout?
Often yes, because higher wattage means a larger power stage. But the cutout size follows the chosen module, not the wattage alone — always use the outline drawing.
How is the module fixed in the cutout?
Common methods are clip-on spring clips, screw fixing from the underside, or flush mounting. The compatible material thickness range is specified by the supplier.
