USB Type-C receptacle cutout dimensions for an enclosure

Short answer: size the opening from the shell envelope plus 0.25 mm [0.010 in] per side. The common 8.94 x 3.26 mm Type-C receptacle shell then needs a 9.44 x 3.76 mm cutout with full-radius R1.5 mm corners. Draw the corners full radius, the way the USB Type-C specification recommends for the receptacle outline. Plan the seal at the same time: a solder-bucket receptacle through a plain hole turns a Type 4X / IP66 wall into a splash path. You need two dimensions from the connector drawing and one rule from this page, and the hole is decided.

The shell dimensions you are cutting for

A Type-C receptacle's outside profile is a folded, stamped shell: flat faces with four corner bends. Datasheets print the envelope, 8.94 mm wide by 3.26 mm tall [0.352 x 0.128 in], but they routinely skip the bend radius, which is exactly the dimension your corners need. The table collects what published drawings and 3D models of common receptacle shells show.

Measure the part in your hand before you commit to a number. Calipers across the shell take half a minute and settle what the drawing leaves out; one measured model reads 0.10 mm shorter in height than its printed 3.26 mm, and 0.10 mm is a fifth of your total gap. Where a drawing prints a value to three decimals with no tolerance, expect about ±0.05 mm and let the gap absorb it. If your connector carries a molded sealing gasket, the gasket's outside dimensions govern the cutout instead, and the shell numbers stop applying.

Sizing the cutout for an 8.94 x 3.26 mm shell at 0.25 mm per side

Inputs. Shell envelope 8.94 x 3.26 mm, from the connector drawing (table above). Gap 0.25 mm [0.010 in] per side, the working value for a pass-through shell. It swallows the unprinted envelope tolerance and the cut's own edge quality, yet keeps the shell located. Shell corner radius R1.2 to R1.3 mm, from the published drawing and the measured model.

Rule. Add the gap to both ends of each envelope dimension, then add the same gap to the shell radius, so the aperture corners stay parallel to the shell corners.

Arithmetic:

• Width: 8.94 + (2 x 0.25) = 9.44 mm [0.372 in]
• Height: 3.26 + (2 x 0.25) = 3.76 mm [0.148 in]
• Corner radius: R1.25 + 0.25 = R1.5 mm
• Worst-case fit: a shell at the top of its height tolerance stands 3.26 + 0.15 = 3.41 mm tall, leaving (3.76 - 3.41) / 2 = 0.175 mm of side clearance, still a sliding fit under finger pressure

Result. Cut the aperture at the calculated size, four corners at R1.5 mm, with no flats where the arcs meet the straight sides.

Decision. A bare or flanged shell without a gasket takes the calculated aperture as sized. A shell with a molded sealing gasket takes the gasket's outside dimensions from its drawing. A receptacle on its own small PCB behind the wall, sealed by a panel-mount connector in the same hole, keeps the same aperture: the panel-mount USB connector: pigtail or daughterboard choice changes the parts around the hole, not the hole. For a larger panel aperture, the same envelope-plus-gap arithmetic runs longer, as in sizing a panel cutout for a bare OLED display.

The per-side gap is the same clearance logic that sizes molded case gaps: 0.3 mm per side clears a ±0.3 mm molded part, and a Type-C shell needs only 0.25 mm because its tolerances are tighter (same clearance logic at 0.3 mm per side for ±0.3 mm parts).

What you need

Nothing exotic; the hole is small and the parts are cheap:

• The connector in hand, plus its drawing or the distributor's 3D model
• Digital calipers with 0.01 mm resolution, to measure the real shell
• Layout fluid or masking tape and a scriber, for the scribed outline
• Centre punch and a 3 mm drill: a 3 mm hole is exactly R1.5 mm, so the four pilot holes are the corners
• A jigsaw with a fine metal-cutting blade, 24 teeth per inch or finer, plus cutting oil; how the cutting methods compare for a clean square cutout covers the trade-offs on stainless
• A small file and an abrasive pad, for deburring both faces
• The sealing hardware: a gasketed panel-mount USB-C pass-through, or a panel-mount receptacle with its sealing gasket, rated to at least the wall's level

If the opening goes into a rated stainless wall, order it cut rather than cutting it. The cutout designer lays out holes, glands and operators on any face, checks spacing and exports the layout with the quote request, and the custom stainless cutouts page weighs a standard body with new openings against a fully custom one. The factory cuts, deburrs and finishes to the approved drawing, and the enclosure is delivered in 10 business days from your approval. For a prototype on a spare or unrated wall, the steps below finish in one sitting.

Cutting and sealing the opening, step by step

1. Measure the shell. Calipers across the widest and tallest points; write both numbers down. You expect 8.94 x 3.26 mm, and anything within ±0.15 mm keeps the sizing above valid. A molded gasket on the part means you measure the gasket and size the hole to it.
2. Lay out the aperture. Scribe the calculated outline, mark the corner arc centres 1.5 mm in from each edge, and centre-punch them.
3. Drill the four corner pilots at 3 mm. Each pilot is exactly R1.5 mm, the corner radius you want, and gives the blade a turning point.
4. Cut the straight runs just inside the line. Slow speed, cutting oil, fine blade; stainless work-hardens, so keep the blade moving and let the teeth cut. Wear gloves and eye protection: stainless swarf is razor sharp.
5. File to the line. Bring each side to the scribed dimension, checking with calipers at the midpoints and beside each corner, and blend each pilot into the side walls so the radius runs full.
6. Deburr both faces. An outer-face burr slices the gasket; an inner-face burr catches the cable.
7. Dry-fit the connector. The shell should slide through under finger pressure with about 0.25 mm of daylight on each side. If it binds, open the tight side by 0.10 mm at a time; if it rattles, the hole has passed 0.5 mm of gap per side, and a re-cut beats a shim.
8. Seal the penetration. Fit the gasketed pass-through or the receptacle with its gasket against the outer face, compress it evenly to about 25-30 % of its free thickness, and tighten the nut or flange screws in a cross pattern. Leave about 30 mm clear behind the wall for the body, the nut and the first cable bend; the USB-C overmold clearance guide covers the space the plug needs outside.

If USB crosses the wall as a captive cable instead of a matable receptacle, a molded pass-through keeps everything dry and skips the plug-versus-hole problem; USB pass-through on a sealed enclosure lays out that version. For a wall that sees washdown, keeping USB and ethernet ports waterproof picks up where this hole leaves off.

Checks before you close the box

• Plug cycle. Insert a USB-C plug twenty times. Scrape lines on the overmold mean a corner is short of full radius; open that corner with the file rather than widening the slot.
• Dimensions. Calipers read the calculated width and height, and every corner blends into the sides without a flat.
• Water. Hose the fitted connector from several angles for 3 minutes and inspect inside for damp. The bar is high: IP66 is the powerful-jets rating, tested with a 12.5 mm nozzle at 100 L/min per IEC 60529, so a light misting proves little.
• Rating bookkeeping. Our wall-mount and HMI enclosures come in 304 or 316L stainless, rated NEMA 4X / IP66 by the manufacturer; not UL listed. The lowest-rated part in the wall sets the assembly rating, so the connector or pass-through you fitted has to seal at the same level.

Mistakes that cost the fit or the seal

• Sizing from the flats. 6.69 x 0.70 mm describes the sheet before the bends, and the bends form the outside of the shell. That hole comes out 2.25 mm narrow and 2.56 mm short, and you find out with a file.
• Square corners. An internal square corner needs file work that eats the hole oversize, and sharp corners are where gaskets tear. The four 3 mm pilots give you the radius for free.
• Copying a different maker's shell. The measured model reads 8.95 x 3.16 mm against the 8.94 x 3.26 mm drawing. Trust your calipers over the last part you fitted.
• A bare receptacle in a rated wall. Shell seams and solder joints are not watertight. Decide the seal before the saw comes out, and put the gasketed part on the order with the hole.

Cut the envelope plus 0.25 mm per side with R1.5 mm corners for a bare shell, follow the gasket outline for a sealed part, and the wall stays rated.

Catalog dimensions to compare

Compare these catalog dimensions with your component layout. Open each enclosure for its rating, material and usable space, then check those specifications against your application.

Questions