PG Thread Chart (DIN 40430): PG7–PG48 Tap Drill & Metric
Standardized under DIN 40430, PG (Panzergewinde) electrical cable gland threads use a wide 80° flank angle and shallow thread depth h3 = 0.45P for thin-walled conduit. Size PG13.5 has major diameter 20.40 mm at 18 TPI, uses a Ø19.1 mm tap drill, and maps to M20×1.5.
DIN 40430 PG Cable Gland Thread Dimensions, Tap Drill & Knock-Out Calculator (PG7–PG48)
Lookup DIN 40430 80°-flank Panzergewinde major diameter d, TPI and pitch P, thread depth h3 = 0.45P, pre-tap drill size, panel knock-out clearance hole, and EN 60423 metric replacement size (M12×1.5 to M63×1.5).
Why Does DIN 40430 PG Thread Use an 80° Flank Angle and Inch TPI?
When repairing German CNC machine tool electrical cabinets, Siemens spindle motor terminal boxes, or Heidenhain linear scale housings, machinists frequently encounter thread diameters that match neither standard ISO metric fine threads in our metric tap drill chart nor British Whitworth pipe threads in our BSPP/BSPT pipe thread chart. Originally standardized by DIN German Institute for Standardization in DIN 40430, the numbers 7, 9, 11, 13.5, 16, 21, 29, 36, 42, 48 denoted the maximum bore diameter (in millimeters) of the old lead-lined steel conduit pipe rather than the external thread diameter.
Because thin electrical conduit walls would split under the deep 0.6134P cut of a 60° ISO thread or the 0.6403P cut of a 55° Whitworth thread, DIN 40430 widens the included flank angle to 80° (40° half-angle). The fundamental triangle height is H = 0.5P · cot(40°) = 0.595877P, the thread depth is truncated to h3 = 0.45P, and crests and roots are rounded with radius r = 0.073P. Interestingly, the pitch of every PG size is defined in imperial threads per inch: 20 TPI for PG7, 18 TPI for PG9 through PG16, and 16 TPI for PG21 through PG48.
Convention and sources. The root diameter d1 is the manufacturer's published value from Heyco's DIN 40430 PG hub specifications for every size from PG7 to PG48. The pitch diameter d2 is the published value from the same Heyco page; d − h3 (with h3 = 0.45P) is shown only as a derived reference and can differ from it by up to about 0.04 mm. The pre-tap drill is derived from the core and is not verified against DIN 40430; check the standard before using it for a tolerance decision. The wrench flats of PG13.5 (24 mm here, 23 mm in some distributor catalogues) and PG21 (33 mm here, 32 mm in some distributor catalogues) conflict between sources and are not fixed to one value until DIN 40430 is checked. The wrench column therefore shows the range, and the DIN 40430 wrench values were not checked against the standard in this build.
| PG Size | Major Diameter d | TPI & Pitch P | Pitch Ø d2 (published, Heyco) / Ø d1 (published root, Heyco) | Pre-Tap Drill Size (derived) | Standard Clearance Hole Ø |
|---|---|---|---|---|---|
| PG7 | Ø12.50 mm (0.4921") | 20 TPI (1.270 mm) | Ø11.89 mm (Heyco published) / Ø11.28 mm (Heyco root) | Ø11.3 mm (0.4449") | Ø12.8 mm |
| PG9 | Ø15.20 mm (0.5984") | 18 TPI (1.411 mm) | Ø14.53 mm (Heyco published) / Ø13.86 mm (Heyco root) | Ø13.9 mm (0.5472") | Ø15.5 mm |
| PG11 | Ø18.60 mm (0.7323") | 18 TPI (1.411 mm) | Ø17.93 mm (Heyco published) / Ø17.26 mm (Heyco root) | Ø17.3 mm (0.6811") | Ø18.9 mm |
| PG13.5 | Ø20.40 mm (0.8031") | 18 TPI (1.411 mm) | Ø19.73 mm (Heyco published) / Ø19.06 mm (Heyco root) | Ø19.1 mm (0.7520") | Ø20.7 mm |
| PG16 | Ø22.50 mm (0.8858") | 18 TPI (1.411 mm) | Ø21.83 mm (Heyco published) / Ø21.16 mm (Heyco root) | Ø21.2 mm (0.8346") | Ø22.8 mm |
| PG21 | Ø28.30 mm (1.1142") | 16 TPI (1.587 mm) | Ø27.54 mm (Heyco published) / Ø26.78 mm (Heyco root) | Ø26.8 mm (1.0551") | Ø28.6 mm |
| PG29 | Ø37.00 mm (1.4567") | 16 TPI (1.587 mm) | Ø36.24 mm (Heyco published) / Ø35.48 mm (Heyco root) | Ø35.5 mm (1.3976") | Ø37.4 mm |
| PG36 | Ø47.00 mm (1.8504") | 16 TPI (1.587 mm) | Ø46.24 mm (Heyco published) / Ø45.48 mm (Heyco root) | Ø45.5 mm (1.7913") | Ø47.4 mm |
| PG42 | Ø54.00 mm (2.1260") | 16 TPI (1.587 mm) | Ø53.24 mm (Heyco published) / Ø52.48 mm (Heyco root) | Ø52.5 mm (2.0669") | Ø54.4 mm |
| PG48 | Ø59.30 mm (2.3346") | 16 TPI (1.587 mm) | Ø58.54 mm (Heyco published) / Ø57.78 mm (Heyco root) | Ø57.8 mm (2.2756") | Ø59.7 mm |
Converting Legacy PG7–PG48 Glands to EN 60423 Metric (M12×1.5 to M63×1.5)
Although EN 60423 replaced PG threads with fine-pitch ISO metric cable glands (all using a constant 1.5 mm pitch from M12×1.5 to M63×1.5), millions of legacy motor housings and junction boxes remain in service worldwide. Notice that PG13.5 (Ø20.4 mm × 1.411 mm pitch) and M20×1.5 (Ø20.0 mm × 1.500 mm pitch) differ by only 0.4 mm on diameter and 0.089 mm on pitch—never force an M20 brass gland into a tapped PG13.5 cast-iron boss or it will cross-thread after two turns! For North American tapered conduit hubs, compare against our NPT pipe tap drill chart.
| Legacy PG Thread | EN 60423 Metric Replacement | Cable Clamping Range | Wrench Hex Flats (AF) | 80° Thread Depth h3 & Radius r |
|---|---|---|---|---|
| PG7 (Ø12.5 mm) | M12×1.5 | 3.0–6.5 mm | 15 mm | h3 = 0.572 mm / r = 0.093 mm |
| PG9 (Ø15.2 mm) | M16×1.5 | 4.0–8.0 mm | 19 mm | h3 = 0.635 mm / r = 0.103 mm |
| PG11 (Ø18.6 mm) | M16×1.5 / M20×1.5 | 5.0–10.0 mm | 22 mm | h3 = 0.635 mm / r = 0.103 mm |
| PG13.5 (Ø20.4 mm) | M20×1.5 | 6.0–12.0 mm | 23–24 mm | h3 = 0.635 mm / r = 0.103 mm |
| PG16 (Ø22.5 mm) | M20×1.5 / M25×1.5 | 10.0–14.0 mm | 27 mm | h3 = 0.635 mm / r = 0.103 mm |
| PG21 (Ø28.3 mm) | M25×1.5 / M32×1.5 | 13.0–18.0 mm | 32–33 mm | h3 = 0.714 mm / r = 0.116 mm |
| PG29 (Ø37.0 mm) | M32×1.5 / M40×1.5 | 18.0–25.0 mm | 42 mm | h3 = 0.714 mm / r = 0.116 mm |
| PG36 (Ø47.0 mm) | M50×1.5 | 22.0–32.0 mm | 53 mm | h3 = 0.714 mm / r = 0.116 mm |
| PG42 (Ø54.0 mm) | M50×1.5 / M63×1.5 | 30.0–38.0 mm | 60 mm | h3 = 0.714 mm / r = 0.116 mm |
| PG48 (Ø59.3 mm) | M63×1.5 | 34.0–44.0 mm | 65 mm | h3 = 0.714 mm / r = 0.116 mm |
Worked Examples: Tapping PG9 Sensor Ports & Punching PG21 Motor Boxes
Worked Example 1 (Tapping a PG9 Port in an Aluminum Proximity Switch Housing): Our engine shows that PG9 has major diameter d = 15.20 mm (0.5984") and pitch 1.411 mm (18 TPI), with published pitch diameter d2 = 14.53 mm (Heyco; the derived d − h3 = 14.565 mm is a reference only) and published root diameter d1 = 13.86 mm (Heyco). Drill the boss to Ø13.9 mm (0.5472") before tapping or thread-milling with an 80° single-form cutter in our CNC thread milling calculator.
Worked Example 2 (PG21 Spindle Motor Box with Close O-Ring Seal): For a PG21 gland (d = 28.30 mm, 16 TPI) mounted through a sheet-metal panel with a locknut and face O-ring, select the close clearance hole Ø28.5 mm (1.1220"). The Ø26.8 mm tap drill is the core size for cutting the thread and is not a clearance hole. Size the sheet-metal knockout force in our sheet metal hole punching tonnage calculator.
Metric equivalents use International Organization for Standardization (ISO) ISO 261 pitches with International Organization for Standardization (ISO) ISO 965 tolerance classes, and inch figures use the exact 25.4 mm-per-inch factor from NIST Special Publication 811.
Before tapping, check the pre-tap drill against the value above with a pin gage, and check the knock-out hole with a plug gage at the nominal size. Confirm the thread with a PG thread gage or a go/no-go ring at the mouth. The tap drill is derived from the root diameter and is not verified against DIN 40430, so check it against the standard before a tolerance decision.
Cite this page
ToolSpecVault Engineering Data Team. (2026, November 2). PG Thread Chart (DIN 40430): PG7–PG48 Tap Drill & Metric. ToolSpecVault. https://toolspecvault.com/pg-cable-gland-thread-dimensions-tap-drill-chart/