Whether you are designing a part, programming a CNC machine or selecting masking for surface treatment, accurate thread dimensions matter. This reference guide lists major, pitch and minor diameter limits and tap-drill guidance for ISO metric coarse and fine, UNC, UNF and parallel BSP (G) threads.
The tables are a practical reference, not a substitute for the controlled edition of the relevant standard or the requirements of a drawing. Confirm the specified thread form, class, thread engagement and manufacturing method before releasing a part.
1. ISO Metric Coarse Threads (M) — Tolerance Class 6g / 6H
ISO metric coarse threads are general-purpose metric threads. This section provides a reference for 6g external and 6H internal tolerances; confirm the class specified on the drawing and the current controlled standard before manufacture.
1a. External Threads (Bolts) — Class 6g
| Thread | Pitch (mm) | Major Ø Max (mm) | Major Ø Min (mm) | Pitch Ø Max (mm) | Pitch Ø Min (mm) | Minor Ø Max (mm) | Minor Ø Min (mm) | Tap Drill (mm) |
|---|---|---|---|---|---|---|---|---|
| M1 | 0.25 | 0.980 | 0.920 | 0.820 | 0.770 | 0.710 | 0.610 | 0.75 |
| M1.2 | 0.25 | 1.180 | 1.120 | 1.020 | 0.970 | 0.910 | 0.810 | 0.95 |
| M1.4 | 0.30 | 1.380 | 1.310 | 1.180 | 1.120 | 1.060 | 0.940 | 1.1 |
| M1.6 | 0.35 | 1.571 | 1.496 | 1.354 | 1.291 | 1.221 | 1.075 | 1.25 |
| M2 | 0.40 | 1.981 | 1.886 | 1.721 | 1.654 | 1.548 | 1.384 | 1.6 |
| M2.5 | 0.45 | 2.480 | 2.380 | 2.208 | 2.138 | 2.013 | 1.838 | 2.05 |
| M3 | 0.50 | 2.980 | 2.874 | 2.655 | 2.580 | 2.436 | 2.253 | 2.5 |
| M3.5 | 0.60 | 3.479 | 3.354 | 3.110 | 3.022 | 2.850 | 2.636 | 2.9 |
| M4 | 0.70 | 3.978 | 3.838 | 3.523 | 3.433 | 3.220 | 2.980 | 3.3 |
| M5 | 0.80 | 4.976 | 4.826 | 4.456 | 4.361 | 4.105 | 3.838 | 4.2 |
| M6 | 1.00 | 5.974 | 5.794 | 5.324 | 5.212 | 4.891 | 4.596 | 5.0 |
| M7 | 1.00 | 6.974 | 6.794 | 6.324 | 6.212 | 5.891 | 5.596 | 6.0 |
| M8 | 1.25 | 7.972 | 7.760 | 7.160 | 7.042 | 6.619 | 6.272 | 6.8 |
| M10 | 1.50 | 9.968 | 9.732 | 8.994 | 8.862 | 8.344 | 7.938 | 8.5 |
| M12 | 1.75 | 11.966 | 11.701 | 10.829 | 10.679 | 10.072 | 9.602 | 10.2 |
| M14 | 2.00 | 13.962 | 13.682 | 12.663 | 12.503 | 11.800 | 11.271 | 12.0 |
| M16 | 2.00 | 15.962 | 15.682 | 14.663 | 14.503 | 13.800 | 13.271 | 14.0 |
| M18 | 2.50 | 17.958 | 17.623 | 16.334 | 16.164 | 15.217 | 14.617 | 15.5 |
| M20 | 2.50 | 19.958 | 19.623 | 18.334 | 18.164 | 17.217 | 16.617 | 17.5 |
| M22 | 2.50 | 21.958 | 21.623 | 20.334 | 20.164 | 19.217 | 18.617 | 19.5 |
| M24 | 3.00 | 23.952 | 23.577 | 22.003 | 21.803 | 20.752 | 20.046 | 21.0 |
| M27 | 3.00 | 26.952 | 26.577 | 25.003 | 24.803 | 23.752 | 23.046 | 24.0 |
| M30 | 3.50 | 29.947 | 29.522 | 27.674 | 27.462 | 26.211 | 25.441 | 26.5 |
| M33 | 3.50 | 32.947 | 32.522 | 30.674 | 30.462 | 29.211 | 28.441 | 29.5 |
| M36 | 4.00 | 35.940 | 35.465 | 33.342 | 33.118 | 31.670 | 30.799 | 32.0 |
| M39 | 4.00 | 38.940 | 38.465 | 36.342 | 36.118 | 34.670 | 33.799 | 35.0 |
| M42 | 4.50 | 41.937 | 41.437 | 39.014 | 38.778 | 37.129 | 36.178 | 37.5 |
| M45 | 4.50 | 44.937 | 44.437 | 42.014 | 41.778 | 40.129 | 39.178 | 40.5 |
| M48 | 5.00 | 47.929 | 47.399 | 44.681 | 44.431 | 42.587 | 41.537 | 43.0 |
| M52 | 5.00 | 51.929 | 51.399 | 48.681 | 48.431 | 46.587 | 45.537 | 47.0 |
| M56 | 5.50 | 55.925 | 55.365 | 52.353 | 52.088 | 50.046 | 48.896 | 50.5 |
| M60 | 5.50 | 59.925 | 59.365 | 56.353 | 56.088 | 54.046 | 52.896 | 54.5 |
| M64 | 6.00 | 63.920 | 63.320 | 60.023 | 59.743 | 57.505 | 56.255 | 58.0 |
| M68 | 6.00 | 67.920 | 67.320 | 64.023 | 63.743 | 61.505 | 60.255 | 62.0 |
| M72 | 6.00 | 71.920 | 71.320 | 68.023 | 67.743 | 65.505 | 64.255 | 66.0 |
| M80 | 6.00 | 79.920 | 79.320 | 76.023 | 75.743 | 73.505 | 72.255 | 74.0 |
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What do you need to mask?
1b. Internal Threads (Nuts) — Class 6H
| Thread | Pitch (mm) | Major Ø Min (mm) | Major Ø Max (mm) | Pitch Ø Min (mm) | Pitch Ø Max (mm) | Minor Ø Min (mm) | Minor Ø Max (mm) |
|---|---|---|---|---|---|---|---|
| M1 | 0.25 | 1.000 | 1.095 | 0.838 | 0.908 | 0.729 | 0.785 |
| M1.2 | 0.25 | 1.200 | 1.295 | 1.038 | 1.108 | 0.929 | 0.985 |
| M1.4 | 0.30 | 1.400 | 1.510 | 1.205 | 1.283 | 1.075 | 1.142 |
| M1.6 | 0.35 | 1.600 | 1.736 | 1.373 | 1.458 | 1.221 | 1.321 |
| M2 | 0.40 | 2.000 | 2.148 | 1.740 | 1.830 | 1.567 | 1.679 |
| M2.5 | 0.45 | 2.500 | 2.660 | 2.208 | 2.303 | 2.013 | 2.138 |
| M3 | 0.50 | 3.000 | 3.172 | 2.675 | 2.775 | 2.459 | 2.599 |
| M3.5 | 0.60 | 3.500 | 3.699 | 3.110 | 3.222 | 2.850 | 3.010 |
| M4 | 0.70 | 4.000 | 4.219 | 3.545 | 3.663 | 3.242 | 3.422 |
| M5 | 0.80 | 5.000 | 5.240 | 4.480 | 4.605 | 4.134 | 4.334 |
| M6 | 1.00 | 6.000 | 6.300 | 5.350 | 5.500 | 4.917 | 5.153 |
| M7 | 1.00 | 7.000 | 7.300 | 6.350 | 6.500 | 5.917 | 6.153 |
| M8 | 1.25 | 8.000 | 8.376 | 7.188 | 7.348 | 6.647 | 6.912 |
| M10 | 1.50 | 10.000 | 10.400 | 9.026 | 9.206 | 8.376 | 8.676 |
| M12 | 1.75 | 12.000 | 12.450 | 10.863 | 11.063 | 10.106 | 10.441 |
| M14 | 2.00 | 14.000 | 14.500 | 12.701 | 12.913 | 11.835 | 12.210 |
| M16 | 2.00 | 16.000 | 16.500 | 14.701 | 14.913 | 13.835 | 14.210 |
| M18 | 2.50 | 18.000 | 18.600 | 16.376 | 16.600 | 15.294 | 15.744 |
| M20 | 2.50 | 20.000 | 20.600 | 18.376 | 18.600 | 17.294 | 17.744 |
| M22 | 2.50 | 22.000 | 22.600 | 20.376 | 20.600 | 19.294 | 19.744 |
| M24 | 3.00 | 24.000 | 24.700 | 22.051 | 22.316 | 20.752 | 21.252 |
| M27 | 3.00 | 27.000 | 27.700 | 25.051 | 25.316 | 23.752 | 24.252 |
| M30 | 3.50 | 30.000 | 30.800 | 27.727 | 28.007 | 26.211 | 26.771 |
| M33 | 3.50 | 33.000 | 33.800 | 30.727 | 31.007 | 29.211 | 29.771 |
| M36 | 4.00 | 36.000 | 36.900 | 33.402 | 33.702 | 31.670 | 32.270 |
| M39 | 4.00 | 39.000 | 39.900 | 36.402 | 36.702 | 34.670 | 35.270 |
| M42 | 4.50 | 42.000 | 43.000 | 39.077 | 39.402 | 37.129 | 37.799 |
| M45 | 4.50 | 45.000 | 46.000 | 42.077 | 42.402 | 40.129 | 40.799 |
| M48 | 5.00 | 48.000 | 49.100 | 44.752 | 45.102 | 42.587 | 43.297 |
| M52 | 5.00 | 52.000 | 53.100 | 48.752 | 49.102 | 46.587 | 47.297 |
| M56 | 5.50 | 56.000 | 57.200 | 52.428 | 52.803 | 50.046 | 50.796 |
| M60 | 5.50 | 60.000 | 61.200 | 56.428 | 56.803 | 54.046 | 54.796 |
| M64 | 6.00 | 64.000 | 65.300 | 60.103 | 60.503 | 57.505 | 58.305 |
| M68 | 6.00 | 68.000 | 69.300 | 64.103 | 64.503 | 61.505 | 62.305 |
| M72 | 6.00 | 72.000 | 73.300 | 68.103 | 68.503 | 65.505 | 66.305 |
| M80 | 6.00 | 80.000 | 81.300 | 76.103 | 76.503 | 73.505 | 74.305 |
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2. ISO Metric Fine Threads (M×P) — Tolerance Class 6g
Metric fine threads have a smaller pitch at a given nominal diameter. The designation includes the pitch, for example M10×1.25; use the drawing to confirm the required series and tolerance class.
2. External Metric Fine Threads — Class 6g
| Thread | Pitch (mm) | Major Ø Max (mm) | Major Ø Min (mm) | Pitch Ø Max (mm) | Pitch Ø Min (mm) | Minor Ø Max (mm) | Minor Ø Min (mm) | Tap Drill (mm) |
|---|---|---|---|---|---|---|---|---|
| M8×1 | 1.00 | 7.974 | 7.794 | 7.324 | 7.212 | 6.891 | 6.596 | 7.0 |
| M10×1 | 1.00 | 9.974 | 9.794 | 9.324 | 9.212 | 8.891 | 8.596 | 9.0 |
| M10×1.25 | 1.25 | 9.972 | 9.760 | 9.160 | 9.042 | 8.619 | 8.272 | 8.75 |
| M12×1 | 1.00 | 11.974 | 11.794 | 11.324 | 11.212 | 10.891 | 10.596 | 11.0 |
| M12×1.25 | 1.25 | 11.972 | 11.760 | 11.160 | 11.042 | 10.619 | 10.272 | 10.75 |
| M12×1.5 | 1.50 | 11.968 | 11.732 | 10.994 | 10.862 | 10.344 | 9.938 | 10.5 |
| M14×1.5 | 1.50 | 13.968 | 13.732 | 12.994 | 12.862 | 12.344 | 11.938 | 12.5 |
| M16×1.5 | 1.50 | 15.968 | 15.732 | 14.994 | 14.862 | 14.344 | 13.938 | 14.5 |
| M18×1.5 | 1.50 | 17.968 | 17.732 | 16.994 | 16.862 | 16.344 | 15.938 | 16.5 |
| M20×1.5 | 1.50 | 19.968 | 19.732 | 18.994 | 18.862 | 18.344 | 17.938 | 18.5 |
| M22×1.5 | 1.50 | 21.968 | 21.732 | 20.994 | 20.862 | 20.344 | 19.938 | 20.5 |
| M24×1.5 | 1.50 | 23.968 | 23.732 | 22.994 | 22.862 | 22.344 | 21.938 | 22.5 |
| M24×2 | 2.00 | 23.962 | 23.682 | 22.663 | 22.503 | 21.800 | 21.271 | 22.0 |
| M27×2 | 2.00 | 26.962 | 26.682 | 25.663 | 25.503 | 24.800 | 24.271 | 25.0 |
| M30×2 | 2.00 | 29.962 | 29.682 | 28.663 | 28.503 | 27.800 | 27.271 | 28.0 |
| M33×2 | 2.00 | 32.962 | 32.682 | 31.663 | 31.503 | 30.800 | 30.271 | 31.0 |
| M36×2 | 2.00 | 35.962 | 35.682 | 34.663 | 34.503 | 33.800 | 33.271 | 34.0 |
| M36×3 | 3.00 | 35.952 | 35.577 | 34.003 | 33.803 | 32.752 | 32.046 | 33.0 |
| M42×2 | 2.00 | 41.962 | 41.682 | 40.663 | 40.503 | 39.800 | 39.271 | 40.0 |
| M42×3 | 3.00 | 41.952 | 41.577 | 40.003 | 39.803 | 38.752 | 38.046 | 39.0 |
| M48×2 | 2.00 | 47.962 | 47.682 | 46.663 | 46.503 | 45.800 | 45.271 | 46.0 |
| M48×3 | 3.00 | 47.952 | 47.577 | 46.003 | 45.803 | 44.752 | 44.046 | 45.0 |
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3. Unified National Coarse (UNC) — Tolerance Class 2A
ASME B1.1 covers Unified inch thread form, series, class, allowance, tolerance and designation. UNC is the coarse pitch series. Sizes below 1/4 inch use a gauge-number designation, for example #8-32.
3. UNC External Threads — Class 2A
| Thread | TPI | Major Ø Max (in) | Major Ø Min (in) | Pitch Ø Max (in) | Pitch Ø Min (in) | Minor Ø Max (in) | Minor Ø Min (in) | Tap Drill |
|---|---|---|---|---|---|---|---|---|
| #0-80 | 80 | 0.0595 | 0.0563 | 0.0514 | 0.0496 | 0.0451 | 0.0422 | #56 / 1.19mm |
| #1-64 | 64 | 0.0724 | 0.0686 | 0.0623 | 0.0603 | 0.0538 | 0.0503 | #53 / 1.51mm |
| #2-56 | 56 | 0.0854 | 0.0813 | 0.0737 | 0.0715 | 0.0641 | 0.0602 | #50 / 1.78mm |
| #3-48 | 48 | 0.0983 | 0.0938 | 0.0847 | 0.0824 | 0.0734 | 0.0691 | #47 / 1.99mm |
| #4-40 | 40 | 0.1113 | 0.1062 | 0.0950 | 0.0925 | 0.0813 | 0.0764 | #43 / 2.26mm |
| #5-40 | 40 | 0.1243 | 0.1192 | 0.1080 | 0.1055 | 0.0943 | 0.0894 | #38 / 2.58mm |
| #6-32 | 32 | 0.1373 | 0.1315 | 0.1169 | 0.1140 | 0.1000 | 0.0942 | #36 / 2.71mm |
| #8-32 | 32 | 0.1633 | 0.1575 | 0.1429 | 0.1400 | 0.1260 | 0.1202 | #29 / 3.45mm |
| #10-24 | 24 | 0.1893 | 0.1822 | 0.1619 | 0.1585 | 0.1411 | 0.1340 | #25 / 3.80mm |
| #12-24 | 24 | 0.2153 | 0.2082 | 0.1879 | 0.1845 | 0.1671 | 0.1600 | #16 / 4.50mm |
| 1/4-20 | 20 | 0.2489 | 0.2408 | 0.2164 | 0.2127 | 0.1876 | 0.1798 | #7 / 5.10mm |
| 5/16-18 | 18 | 0.3110 | 0.3022 | 0.2752 | 0.2712 | 0.2414 | 0.2330 | F / 6.90mm |
| 3/8-16 | 16 | 0.3730 | 0.3637 | 0.3331 | 0.3287 | 0.2938 | 0.2847 | 5/16 / 7.94mm |
| 7/16-14 | 14 | 0.4351 | 0.4248 | 0.3896 | 0.3847 | 0.3447 | 0.3348 | U / 9.40mm |
| 1/2-13 | 13 | 0.4976 | 0.4867 | 0.4472 | 0.4422 | 0.3978 | 0.3871 | 27/64 / 10.72mm |
| 9/16-12 | 12 | 0.5600 | 0.5487 | 0.5065 | 0.5012 | 0.4528 | 0.4416 | 31/64 / 12.30mm |
| 5/8-11 | 11 | 0.6226 | 0.6106 | 0.5644 | 0.5589 | 0.5069 | 0.4950 | 17/32 / 13.49mm |
| 3/4-10 | 10 | 0.7476 | 0.7344 | 0.6832 | 0.6773 | 0.6219 | 0.6091 | 21/32 / 16.67mm |
| 7/8-9 | 9 | 0.8726 | 0.8584 | 0.7995 | 0.7932 | 0.7307 | 0.7167 | 49/64 / 19.45mm |
| 1-8 | 8 | 0.9976 | 0.9820 | 0.9142 | 0.9074 | 0.8376 | 0.8220 | 7/8 / 22.23mm |
| 1 1/8-7 | 7 | 1.1226 | 1.1054 | 1.0257 | 1.0182 | 0.9394 | 0.9218 | 63/64 / 25.00mm |
| 1 1/4-7 | 7 | 1.2476 | 1.2304 | 1.1507 | 1.1432 | 1.0644 | 1.0468 | 1 7/64 / 28.17mm |
| 1 3/8-6 | 6 | 1.3722 | 1.3528 | 1.2585 | 1.2500 | 1.1585 | 1.1390 | 1 7/32 / 31.00mm |
| 1 1/2-6 | 6 | 1.4972 | 1.4778 | 1.3835 | 1.3750 | 1.2835 | 1.2640 | 1 11/32 / 34.13mm |
| 1 3/4-5 | 5 | 1.7462 | 1.7238 | 1.6101 | 1.6001 | 1.4902 | 1.4673 | 1 9/16 / 39.69mm |
| 2-4.5 | 4.5 | 1.9952 | 1.9700 | 1.8476 | 1.8366 | 1.7094 | 1.6843 | 1 25/32 / 45.24mm |
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4. Unified National Fine (UNF) — Tolerance Class 2A
UNF is the fine-pitch Unified series. Confirm the specified series and class from the drawing rather than selecting UNC or UNF by nominal diameter alone.
4. UNF External Threads — Class 2A
| Thread | TPI | Major Ø Max (in) | Major Ø Min (in) | Pitch Ø Max (in) | Pitch Ø Min (in) | Minor Ø Max (in) | Minor Ø Min (in) | Tap Drill |
|---|---|---|---|---|---|---|---|---|
| #0-80 | 80 | 0.0595 | 0.0563 | 0.0514 | 0.0496 | 0.0451 | 0.0422 | #56 / 1.19mm |
| #1-72 | 72 | 0.0724 | 0.0689 | 0.0634 | 0.0615 | 0.0560 | 0.0527 | #53 / 1.51mm |
| #2-64 | 64 | 0.0854 | 0.0816 | 0.0753 | 0.0733 | 0.0671 | 0.0633 | #50 / 1.78mm |
| #3-56 | 56 | 0.0983 | 0.0942 | 0.0866 | 0.0844 | 0.0764 | 0.0723 | #45 / 2.08mm |
| #4-48 | 48 | 0.1113 | 0.1068 | 0.0977 | 0.0954 | 0.0864 | 0.0820 | #42 / 2.36mm |
| #5-44 | 44 | 0.1243 | 0.1195 | 0.1094 | 0.1069 | 0.0971 | 0.0924 | #37 / 2.64mm |
| #6-40 | 40 | 0.1373 | 0.1322 | 0.1209 | 0.1183 | 0.1073 | 0.1023 | #33 / 2.87mm |
| #8-36 | 36 | 0.1633 | 0.1577 | 0.1452 | 0.1424 | 0.1299 | 0.1245 | #29 / 3.45mm |
| #10-32 | 32 | 0.1893 | 0.1835 | 0.1688 | 0.1659 | 0.1519 | 0.1461 | #21 / 4.04mm |
| #12-28 | 28 | 0.2153 | 0.2088 | 0.1920 | 0.1887 | 0.1722 | 0.1657 | #14 / 4.62mm |
| 1/4-28 | 28 | 0.2489 | 0.2424 | 0.2256 | 0.2223 | 0.2058 | 0.1993 | #3 / 5.41mm |
| 5/16-24 | 24 | 0.3110 | 0.3039 | 0.2844 | 0.2808 | 0.2614 | 0.2540 | I / 6.76mm |
| 3/8-24 | 24 | 0.3730 | 0.3659 | 0.3464 | 0.3428 | 0.3234 | 0.3160 | Q / 8.33mm |
| 7/16-20 | 20 | 0.4351 | 0.4271 | 0.4027 | 0.3987 | 0.3757 | 0.3675 | 25/64 / 9.92mm |
| 1/2-20 | 20 | 0.4976 | 0.4896 | 0.4652 | 0.4612 | 0.4382 | 0.4300 | 29/64 / 11.51mm |
| 9/16-18 | 18 | 0.5601 | 0.5515 | 0.5248 | 0.5205 | 0.4943 | 0.4853 | 33/64 / 13.10mm |
| 5/8-18 | 18 | 0.6226 | 0.6140 | 0.5873 | 0.5830 | 0.5568 | 0.5478 | 37/64 / 14.68mm |
| 3/4-16 | 16 | 0.7476 | 0.7381 | 0.7082 | 0.7036 | 0.6733 | 0.6636 | 11/16 / 17.46mm |
| 7/8-14 | 14 | 0.8726 | 0.8621 | 0.8272 | 0.8221 | 0.7874 | 0.7769 | 13/16 / 20.64mm |
| 1-12 | 12 | 0.9976 | 0.9862 | 0.9432 | 0.9378 | 0.8978 | 0.8864 | 59/64 / 23.42mm |
| 1 1/8-12 | 12 | 1.1226 | 1.1112 | 1.0682 | 1.0628 | 1.0228 | 1.0114 | 1 3/64 / 26.59mm |
| 1 1/4-12 | 12 | 1.2476 | 1.2362 | 1.1932 | 1.1878 | 1.1478 | 1.1364 | 1 11/64 / 29.76mm |
| 1 3/8-12 | 12 | 1.3726 | 1.3612 | 1.3182 | 1.3128 | 1.2728 | 1.2614 | 1 19/64 / 32.94mm |
| 1 1/2-12 | 12 | 1.4976 | 1.4862 | 1.4432 | 1.4378 | 1.3978 | 1.3864 | 1 27/64 / 36.11mm |
On smaller screens, swipe or scroll horizontally to view the full table.
5. British Standard Pipe Parallel (BSP / G) — ISO 228
BSP parallel (G) threads are used for pipe and fluid-system connections. The nominal size refers to the pipe bore, not the measured thread diameter. In a BSPP/G connection, sealing is normally achieved at a mating face by the specified O-ring, bonded seal or soft washer, not by the parallel threads alone; verify the fitting design and seal specification.
5. BSP / G Parallel Threads
| Thread | TPI | OD Max (mm) | OD Min (mm) | Pitch Ø Max (mm) | Pitch Ø Min (mm) | Minor Ø Max (mm) | Minor Ø Min (mm) | Tap Drill (mm) |
|---|---|---|---|---|---|---|---|---|
| G 1/16 | 28 | 7.723 | 7.638 | 7.142 | 7.072 | 6.561 | 6.461 | 6.8 |
| G 1/8 | 28 | 9.728 | 9.643 | 9.147 | 9.077 | 8.566 | 8.466 | 8.8 |
| G 1/4 | 19 | 13.157 | 13.045 | 12.301 | 12.211 | 11.445 | 11.295 | 11.8 |
| G 3/8 | 19 | 16.662 | 16.550 | 15.806 | 15.716 | 14.950 | 14.800 | 15.3 |
| G 1/2 | 14 | 20.955 | 20.820 | 19.793 | 19.683 | 18.631 | 18.431 | 19.1 |
| G 5/8 | 14 | 22.911 | 22.776 | 21.749 | 21.639 | 20.587 | 20.387 | 21.1 |
| G 3/4 | 14 | 26.441 | 26.306 | 25.279 | 25.169 | 24.117 | 23.917 | 24.6 |
| G 7/8 | 14 | 30.201 | 30.066 | 29.039 | 28.929 | 27.877 | 27.677 | 28.4 |
| G 1 | 11 | 33.249 | 33.089 | 31.770 | 31.640 | 30.291 | 30.041 | 30.8 |
| G 1 1/4 | 11 | 41.910 | 41.750 | 40.431 | 40.301 | 38.952 | 38.702 | 39.5 |
| G 1 1/2 | 11 | 47.803 | 47.643 | 46.324 | 46.194 | 44.845 | 44.595 | 45.4 |
| G 2 | 11 | 59.614 | 59.454 | 58.135 | 58.005 | 56.656 | 56.406 | 57.2 |
| G 2 1/2 | 11 | 75.184 | 75.024 | 73.705 | 73.575 | 72.226 | 71.976 | 72.8 |
| G 3 | 11 | 87.884 | 87.724 | 86.405 | 86.275 | 84.926 | 84.676 | 85.5 |
| G 4 | 11 | see standard | see standard | see standard | see standard | see standard | see standard | 110.9 |
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G 4 note: ISO 228-1:2000 Table 1 lists basic dimensions of 113.030 mm major diameter, 111.551 mm pitch diameter and 110.072 mm minor diameter. These basic dimensions are not tolerance limits. The six max/min cells are not verified because the table does not identify the thread type or tolerance class. For engineering release, use the adopted controlled standard and drawing.
How to Choose Masking Plugs Based on Thread Size
Use the thread data as a starting point when selecting a silicone plug for a threaded hole. A nominal thread size alone does not define the usable opening, the lead-in geometry or the process conditions.
Start with the actual hole geometry
- Compare the plug's lower diameter with the actual minor diameter and entry condition so that the plug can be inserted without damaging the part or the masking element.
- Check that the upper section engages the lead-in or chamfer as needed for the intended masking boundary.
- For blind holes, confirm usable depth, venting and removal access. Measure representative parts where coating build-up, tolerances or pre-treatment can affect fit.
Validate the process, not only the dimensions
Thread dimensions alone do not establish liquid sealing, retention, chemical or bath compatibility, or a reuse count. Validate fit and removal on representative parts under the actual preparation, coating, cure and handling conditions.
For Masking Supply silicone masking parts, the maximum temperature to state is 250 °C. This is a store product-category rating, not evidence of chemical compatibility, immersion performance or suitability for every process. Where adjacent surfaces are masked with tape, the corresponding store maximums are 204 °C for PET tape and 260 °C for polyimide/Kapton tape; assess the complete tape system for the actual exposure.
Select a practical plug configuration
For repeat production, select a configuration that suits the measured hole geometry and handling method. Browse the silicone plug range for standard options. Where access allows, tapered silicone plugs with handles can make placement and removal easier in blind holes.
For unusual thread forms, restricted depths or demanding process conditions, contact us with your part details.