Thread & Tap Drill Chart
ISO Metric (coarse + fine), Unified UNC/UNF/UNEF, NPT/NPTF, BSPP/BSPT and Whitworth BSW/BSF — all in one searchable reference.
Smart search matches designation, standard, pitch/TPI, tap-drill name or major diameter (±2%). Fractions, decimals and units (mm, ") are all understood. Showing 184 of 184 entries.
| Standard | Designation | Pitch / TPI | Major Ø (mm) | Major Ø (in) | Minor Ø (mm) | Tap drill (mm) | Tap drill (name) | Clearance close | Clearance free | Class / Notes |
|---|---|---|---|---|---|---|---|---|---|---|
| ISO-M | M1.6 × 0.35 | 0.35 mm | 1.600 | 0.063 | 1.171 | 1.250 | — | 1.70 | 1.80 | 6g / 6H |
| ISO-M | M2 × 0.4 | 0.4 mm | 2.000 | 0.079 | 1.509 | 1.600 | — | 2.20 | 2.40 | 6g / 6H |
| ISO-M | M2.5 × 0.45 | 0.45 mm | 2.500 | 0.098 | 1.948 | 2.050 | — | 2.70 | 2.90 | 6g / 6H |
| ISO-M | M3 × 0.5 | 0.5 mm | 3.000 | 0.118 | 2.387 | 2.500 | — | 3.20 | 3.40 | 6g / 6H |
| ISO-M | M3.5 × 0.6 | 0.6 mm | 3.500 | 0.138 | 2.764 | 2.900 | — | 3.70 | 3.90 | 6g / 6H |
| ISO-M | M4 × 0.7 | 0.7 mm | 4.000 | 0.157 | 3.141 | 3.300 | — | 4.30 | 4.50 | 6g / 6H |
| ISO-M | M5 × 0.8 | 0.8 mm | 5.000 | 0.197 | 4.019 | 4.200 | — | 5.30 | 5.50 | 6g / 6H |
| ISO-M | M6 × 1 | 1 mm | 6.000 | 0.236 | 4.773 | 5.000 | — | 6.40 | 6.60 | 6g / 6H |
| ISO-M | M7 × 1 | 1 mm | 7.000 | 0.276 | 5.773 | 6.000 | — | 7.40 | 7.60 | 6g / 6H |
| ISO-M | M8 × 1.25 | 1.25 mm | 8.000 | 0.315 | 6.466 | 6.800 | — | 8.40 | 9.00 | 6g / 6H |
| ISO-M | M10 × 1.5 | 1.5 mm | 10.000 | 0.394 | 8.160 | 8.500 | — | 10.50 | 11.00 | 6g / 6H |
| ISO-M | M12 × 1.75 | 1.75 mm | 12.000 | 0.472 | 9.853 | 10.200 | — | 13.00 | 13.50 | 6g / 6H |
| ISO-M | M14 × 2 | 2 mm | 14.000 | 0.551 | 11.546 | 12.000 | — | 15.00 | 15.50 | 6g / 6H |
| ISO-M | M16 × 2 | 2 mm | 16.000 | 0.630 | 13.546 | 14.000 | — | 17.00 | 17.50 | 6g / 6H |
| ISO-M | M18 × 2.5 | 2.5 mm | 18.000 | 0.709 | 14.933 | 15.500 | — | 19.00 | 20.00 | 6g / 6H |
| ISO-M | M20 × 2.5 | 2.5 mm | 20.000 | 0.787 | 16.933 | 17.500 | — | 21.00 | 22.00 | 6g / 6H |
| ISO-M | M22 × 2.5 | 2.5 mm | 22.000 | 0.866 | 18.933 | 19.500 | — | 23.00 | 24.00 | 6g / 6H |
| ISO-M | M24 × 3 | 3 mm | 24.000 | 0.945 | 20.319 | 21.000 | — | 25.00 | 26.00 | 6g / 6H |
| ISO-M | M27 × 3 | 3 mm | 27.000 | 1.063 | 23.319 | 24.000 | — | 28.00 | 30.00 | 6g / 6H |
| ISO-M | M30 × 3.5 | 3.5 mm | 30.000 | 1.181 | 25.706 | 26.500 | — | 31.00 | 33.00 | 6g / 6H |
| ISO-M | M33 × 3.5 | 3.5 mm | 33.000 | 1.299 | 28.706 | 29.500 | — | 34.00 | 36.00 | 6g / 6H |
| ISO-M | M36 × 4 | 4 mm | 36.000 | 1.417 | 31.093 | 32.000 | — | 37.00 | 39.00 | 6g / 6H |
| ISO-M | M39 × 4 | 4 mm | 39.000 | 1.535 | 34.093 | 35.000 | — | 40.00 | 42.00 | 6g / 6H |
| ISO-M | M42 × 4.5 | 4.5 mm | 42.000 | 1.654 | 36.479 | 37.500 | — | 43.00 | 45.00 | 6g / 6H |
| ISO-M | M45 × 4.5 | 4.5 mm | 45.000 | 1.772 | 39.479 | 40.500 | — | 46.00 | 48.00 | 6g / 6H |
| ISO-M | M48 × 5 | 5 mm | 48.000 | 1.890 | 41.866 | 43.000 | — | 50.00 | 52.00 | 6g / 6H |
| ISO-M | M52 × 5 | 5 mm | 52.000 | 2.047 | 45.866 | 47.000 | — | 54.00 | 56.00 | 6g / 6H |
| ISO-M | M56 × 5.5 | 5.5 mm | 56.000 | 2.205 | 49.252 | 50.500 | — | 58.00 | 62.00 | 6g / 6H |
| ISO-M | M60 × 5.5 | 5.5 mm | 60.000 | 2.362 | 53.252 | 54.500 | — | 62.00 | 66.00 | 6g / 6H |
| ISO-M | M64 × 6 | 6 mm | 64.000 | 2.520 | 56.639 | 58.000 | — | 66.00 | 70.00 | 6g / 6H |
| ISO-M | M8 (fine) × 1 | 1 mm | 8.000 | 0.315 | 6.773 | 7.000 | — | 8.40 | 9.00 | 6g / 6H Fine pitch |
| ISO-M | M10 (fine) × 1.25 | 1.25 mm | 10.000 | 0.394 | 8.466 | 8.800 | — | 10.50 | 11.00 | 6g / 6H Fine pitch |
| ISO-M | M10 (fine) × 1 | 1 mm | 10.000 | 0.394 | 8.773 | 9.000 | — | 10.50 | 11.00 | 6g / 6H Fine pitch |
| ISO-M | M12 (fine) × 1.5 | 1.5 mm | 12.000 | 0.472 | 10.160 | 10.500 | — | 13.00 | 13.50 | 6g / 6H Fine pitch |
| ISO-M | M12 (fine) × 1.25 | 1.25 mm | 12.000 | 0.472 | 10.466 | 10.800 | — | 13.00 | 13.50 | 6g / 6H Fine pitch |
| ISO-M | M14 (fine) × 1.5 | 1.5 mm | 14.000 | 0.551 | 12.160 | 12.500 | — | 15.00 | 15.50 | 6g / 6H Fine pitch |
| ISO-M | M16 (fine) × 1.5 | 1.5 mm | 16.000 | 0.630 | 14.160 | 14.500 | — | 17.00 | 17.50 | 6g / 6H Fine pitch |
| ISO-M | M18 (fine) × 1.5 | 1.5 mm | 18.000 | 0.709 | 16.160 | 16.500 | — | 19.00 | 20.00 | 6g / 6H Fine pitch |
| ISO-M | M20 (fine) × 1.5 | 1.5 mm | 20.000 | 0.787 | 18.160 | 18.500 | — | 21.00 | 22.00 | 6g / 6H Fine pitch |
| ISO-M | M22 (fine) × 1.5 | 1.5 mm | 22.000 | 0.866 | 20.160 | 20.500 | — | 23.00 | 24.00 | 6g / 6H Fine pitch |
| ISO-M | M24 (fine) × 2 | 2 mm | 24.000 | 0.945 | 21.546 | 22.000 | — | 25.00 | 26.00 | 6g / 6H Fine pitch |
| ISO-M | M27 (fine) × 2 | 2 mm | 27.000 | 1.063 | 24.546 | 25.000 | — | 28.00 | 30.00 | 6g / 6H Fine pitch |
| ISO-M | M30 (fine) × 2 | 2 mm | 30.000 | 1.181 | 27.546 | 28.000 | — | 31.00 | 33.00 | 6g / 6H Fine pitch |
| ISO-M | M33 (fine) × 2 | 2 mm | 33.000 | 1.299 | 30.546 | 31.000 | — | 34.00 | 36.00 | 6g / 6H Fine pitch |
| ISO-M | M36 (fine) × 3 | 3 mm | 36.000 | 1.417 | 32.319 | 33.000 | — | 37.00 | 39.00 | 6g / 6H Fine pitch |
| ISO-M | M42 (fine) × 3 | 3 mm | 42.000 | 1.654 | 38.319 | 39.000 | — | 43.00 | 45.00 | 6g / 6H Fine pitch |
| ISO-M | M48 (fine) × 3 | 3 mm | 48.000 | 1.890 | 44.319 | 45.000 | — | 50.00 | 52.00 | 6g / 6H Fine pitch |
| UNF | #0-80 UNF | 80 TPI | 1.524 | 0.060 | 1.135 | 1.191 | 3/64 | 1.63 | 1.70 | 2A / 2B |
| UNC | #1-64 UNC | 64 TPI | 1.854 | 0.073 | 1.367 | 1.511 | #53 | 1.93 | 2.03 | 2A / 2B |
| UNF | #1-72 UNF | 72 TPI | 1.854 | 0.073 | 1.422 | 1.511 | #53 | 1.93 | 2.03 | 2A / 2B |
| UNC | #2-56 UNC | 56 TPI | 2.184 | 0.086 | 1.628 | 1.778 | #50 | 2.29 | 2.39 | 2A / 2B |
| UNF | #2-64 UNF | 64 TPI | 2.184 | 0.086 | 1.697 | 1.778 | #50 | 2.29 | 2.39 | 2A / 2B |
| UNC | #3-48 UNC | 48 TPI | 2.515 | 0.099 | 1.864 | 1.994 | #47 | 2.64 | 2.72 | 2A / 2B |
| UNF | #3-56 UNF | 56 TPI | 2.515 | 0.099 | 1.958 | 2.083 | #45 | 2.64 | 2.72 | 2A / 2B |
| UNC | #4-40 UNC | 40 TPI | 2.845 | 0.112 | 2.065 | 2.261 | #43 | 2.95 | 3.05 | 2A / 2B |
| UNF | #4-48 UNF | 48 TPI | 2.845 | 0.112 | 2.195 | 2.375 | #42 | 2.95 | 3.05 | 2A / 2B |
| UNC | #5-40 UNC | 40 TPI | 3.175 | 0.125 | 2.395 | 2.578 | #38 | 3.30 | 3.45 | 2A / 2B |
| UNF | #5-44 UNF | 44 TPI | 3.175 | 0.125 | 2.466 | 2.642 | #37 | 3.30 | 3.45 | 2A / 2B |
| UNC | #6-32 UNC | 32 TPI | 3.505 | 0.138 | 2.532 | 2.705 | #36 | 3.66 | 3.79 | 2A / 2B |
| UNF | #6-40 UNF | 40 TPI | 3.505 | 0.138 | 2.725 | 2.870 | #33 | 3.66 | 3.79 | 2A / 2B |
| UNC | #8-32 UNC | 32 TPI | 4.166 | 0.164 | 3.193 | 3.454 | #29 | 4.29 | 4.50 | 2A / 2B |
| UNF | #8-36 UNF | 36 TPI | 4.166 | 0.164 | 3.299 | 3.454 | #29 | 4.29 | 4.50 | 2A / 2B |
| UNC | #10-24 UNC | 24 TPI | 4.826 | 0.190 | 3.528 | 3.797 | #25 | 4.98 | 5.18 | 2A / 2B |
| UNF | #10-32 UNF | 32 TPI | 4.826 | 0.190 | 3.853 | 4.039 | #21 | 4.98 | 5.18 | 2A / 2B |
| UNC | #12-24 UNC | 24 TPI | 5.486 | 0.216 | 4.188 | 4.496 | #16 | 5.61 | 5.79 | 2A / 2B |
| UNF | #12-28 UNF | 28 TPI | 5.486 | 0.216 | 4.374 | 4.623 | #14 | 5.61 | 5.79 | 2A / 2B |
| UNC | 1/4-20 UNC | 20 TPI | 6.350 | 0.250 | 4.793 | 5.105 | #7 | 6.53 | 6.76 | 2A / 2B |
| UNF | 1/4-28 UNF | 28 TPI | 6.350 | 0.250 | 5.237 | 5.410 | #3 | 6.53 | 6.76 | 2A / 2B |
| UNEF | 1/4-32 UNEF | 32 TPI | 6.350 | 0.250 | 5.377 | 5.558 | 7/32 | 6.53 | 6.76 | 2A / 2B |
| UNC | 5/16-18 UNC | 18 TPI | 7.938 | 0.313 | 6.205 | 6.528 | F | 8.20 | 8.43 | 2A / 2B |
| UNF | 5/16-24 UNF | 24 TPI | 7.938 | 0.313 | 6.640 | 6.909 | I | 8.20 | 8.43 | 2A / 2B |
| UNEF | 5/16-32 UNEF | 32 TPI | 7.938 | 0.313 | 6.965 | 7.142 | 9/32 | 8.20 | 8.43 | 2A / 2B |
| UNC | 3/8-16 UNC | 16 TPI | 9.525 | 0.375 | 7.577 | 7.938 | 5/16 | 9.80 | 10.08 | 2A / 2B |
| UNF | 3/8-24 UNF | 24 TPI | 9.525 | 0.375 | 8.227 | 8.433 | Q | 9.80 | 10.08 | 2A / 2B |
| UNEF | 3/8-32 UNEF | 32 TPI | 9.525 | 0.375 | 8.552 | 8.733 | 11/32 | 9.80 | 10.08 | 2A / 2B |
| UNC | 7/16-14 UNC | 14 TPI | 11.112 | 0.437 | 8.887 | 9.347 | U | 11.51 | 11.91 | 2A / 2B |
| UNF | 7/16-20 UNF | 20 TPI | 11.112 | 0.437 | 9.555 | 9.921 | 25/64 | 11.51 | 11.91 | 2A / 2B |
| UNEF | 7/16-28 UNEF | 28 TPI | 11.112 | 0.437 | 10.000 | 10.320 | 13/32 | 11.51 | 11.91 | 2A / 2B |
| UNC | 1/2-13 UNC | 13 TPI | 12.700 | 0.500 | 10.302 | 10.716 | 27/64 | 13.11 | 13.49 | 2A / 2B |
| UNF | 1/2-20 UNF | 20 TPI | 12.700 | 0.500 | 11.143 | 11.509 | 29/64 | 13.11 | 13.49 | 2A / 2B |
| UNEF | 1/2-28 UNEF | 28 TPI | 12.700 | 0.500 | 11.587 | 11.908 | 15/32 | 13.11 | 13.49 | 2A / 2B |
| UNC | 9/16-12 UNC | 12 TPI | 14.288 | 0.563 | 11.692 | 12.304 | 31/64 | 14.68 | 15.09 | 2A / 2B |
| UNF | 9/16-18 UNF | 18 TPI | 14.288 | 0.563 | 12.555 | 13.096 | 33/64 | 14.68 | 15.09 | 2A / 2B |
| UNEF | 9/16-24 UNEF | 24 TPI | 14.288 | 0.563 | 12.990 | 13.096 | 33/64 | 14.68 | 15.09 | 2A / 2B |
| UNC | 5/8-11 UNC | 11 TPI | 15.875 | 0.625 | 13.043 | 13.495 | 17/32 | 16.28 | 16.66 | 2A / 2B |
| UNF | 5/8-18 UNF | 18 TPI | 15.875 | 0.625 | 14.031 | 14.684 | 37/64 | 16.28 | 16.66 | 2A / 2B |
| UNEF | 5/8-24 UNEF | 24 TPI | 15.875 | 0.625 | 14.577 | 14.684 | 37/64 | 16.28 | 16.66 | 2A / 2B |
| UNC | 3/4-10 UNC | 10 TPI | 19.050 | 0.750 | 15.933 | 16.670 | 21/32 | 19.46 | 19.84 | 2A / 2B |
| UNF | 3/4-16 UNF | 16 TPI | 19.050 | 0.750 | 17.102 | 17.463 | 11/16 | 19.46 | 19.84 | 2A / 2B |
| UNEF | 3/4-20 UNEF | 20 TPI | 19.050 | 0.750 | 17.493 | 17.859 | 45/64 | 19.46 | 19.84 | 2A / 2B |
| UNC | 7/8-9 UNC | 9 TPI | 22.225 | 0.875 | 18.763 | 19.446 | 49/64 | 22.63 | 23.01 | 2A / 2B |
| UNF | 7/8-14 UNF | 14 TPI | 22.225 | 0.875 | 20.000 | 20.638 | 13/16 | 22.63 | 23.01 | 2A / 2B |
| UNEF | 7/8-20 UNEF | 20 TPI | 22.225 | 0.875 | 20.668 | 21.034 | 53/64 | 22.63 | 23.01 | 2A / 2B |
| UNC | 1-8 UNC | 8 TPI | 25.400 | 1.000 | 21.504 | 22.225 | 7/8 | 25.81 | 26.19 | 2A / 2B |
| UNF | 1-12 UNF | 12 TPI | 25.400 | 1.000 | 22.804 | 23.416 | 59/64 | 25.81 | 26.19 | 2A / 2B |
| UNEF | 1-20 UNEF | 20 TPI | 25.400 | 1.000 | 23.843 | 24.209 | 61/64 | 25.81 | 26.19 | 2A / 2B |
| UNC | 1 1/8-7 UNC | 7 TPI | 28.575 | 1.125 | 24.122 | 25.004 | 63/64 | 28.98 | 29.36 | 2A / 2B |
| UNF | 1 1/8-12 UNF | 12 TPI | 28.575 | 1.125 | 25.979 | 26.591 | 1 3/64 | 28.98 | 29.36 | 2A / 2B |
| UNC | 1 1/4-7 UNC | 7 TPI | 31.750 | 1.250 | 27.297 | 28.179 | 1 7/64 | 32.16 | 32.54 | 2A / 2B |
| UNF | 1 1/4-12 UNF | 12 TPI | 31.750 | 1.250 | 29.154 | 29.766 | 1 11/64 | 32.16 | 32.54 | 2A / 2B |
| UNC | 1 1/2-6 UNC | 6 TPI | 38.100 | 1.500 | 32.601 | 34.133 | 1 11/32 | 38.51 | 38.89 | 2A / 2B |
| UNF | 1 1/2-12 UNF | 12 TPI | 38.100 | 1.500 | 35.504 | 36.116 | 1 27/64 | 38.51 | 38.89 | 2A / 2B |
| UNC | 2-4.5 UNC | 4.5 TPI | 50.800 | 2.000 | 43.876 | 45.245 | 1 25/32 | 51.59 | 51.99 | 2A / 2B |
| UNF | 2-12 UNF | 12 TPI | 50.800 | 2.000 | 48.204 | 48.816 | 1 59/64 | 51.59 | 51.99 | 2A / 2B |
| NPT | 1/16"-27 NPT | 27 TPI | 7.938 | 0.313 | 6.205 | 7.142 | 11/32 (R 0.339" reamer) | 8.45 | 8.95 | Class A (general) Taper 1:16 (3/4" per foot). Drill values per Machinery's Handbook. |
| NPT | 1/8"-27 NPT | 27 TPI | 10.287 | 0.405 | 8.552 | 8.733 | 11/32 | 10.79 | 11.30 | Class A (general) Taper 1:16 (3/4" per foot). Drill values per Machinery's Handbook. |
| NPT | 1/4"-18 NPT | 18 TPI | 13.716 | 0.540 | 10.752 | 11.112 | 7/16 | 14.22 | 14.73 | Class A (general) Taper 1:16 (3/4" per foot). Drill values per Machinery's Handbook. |
| NPT | 3/8"-18 NPT | 18 TPI | 17.145 | 0.675 | 14.420 | 14.684 | 37/64 | 17.65 | 18.16 | Class A (general) Taper 1:16 (3/4" per foot). Drill values per Machinery's Handbook. |
| NPT | 1/2"-14 NPT | 14 TPI | 21.336 | 0.840 | 17.869 | 17.859 | 45/64 | 21.84 | 22.35 | Class A (general) Taper 1:16 (3/4" per foot). Drill values per Machinery's Handbook. |
| NPT | 3/4"-14 NPT | 14 TPI | 26.670 | 1.050 | 23.142 | 23.020 | 29/32 | 27.18 | 27.69 | Class A (general) Taper 1:16 (3/4" per foot). Drill values per Machinery's Handbook. |
| NPT | 1"-11.5 NPT | 11.5 TPI | 33.401 | 1.315 | 29.060 | 28.971 | 1 9/64 | 33.91 | 34.42 | Class A (general) Taper 1:16 (3/4" per foot). Drill values per Machinery's Handbook. |
| NPT | 1 1/4"-11.5 NPT | 11.5 TPI | 42.164 | 1.660 | 37.785 | 37.704 | 1 31/64 | 42.67 | 43.18 | Class A (general) Taper 1:16 (3/4" per foot). Drill values per Machinery's Handbook. |
| NPT | 1 1/2"-11.5 NPT | 11.5 TPI | 48.260 | 1.900 | 43.853 | 43.658 | 1 23/32 | 48.77 | 49.28 | Class A (general) Taper 1:16 (3/4" per foot). Drill values per Machinery's Handbook. |
| NPT | 2"-11.5 NPT | 11.5 TPI | 60.325 | 2.375 | 55.941 | 55.563 | 2 3/16 | 60.83 | 61.34 | Class A (general) Taper 1:16 (3/4" per foot). Drill values per Machinery's Handbook. |
| NPT | 2 1/2"-8 NPT | 8 TPI | 73.025 | 2.875 | 66.535 | 66.675 | 2 5/8 | 73.53 | 74.04 | Class A (general) Taper 1:16 (3/4" per foot). Drill values per Machinery's Handbook. |
| NPT | 3"-8 NPT | 8 TPI | 88.900 | 3.500 | 82.311 | 82.550 | 3 1/4 | 89.41 | 89.92 | Class A (general) Taper 1:16 (3/4" per foot). Drill values per Machinery's Handbook. |
| NPT | 4"-8 NPT | 8 TPI | 114.300 | 4.500 | 107.528 | 107.950 | 4 1/4 | 114.81 | 115.32 | Class A (general) Taper 1:16 (3/4" per foot). Drill values per Machinery's Handbook. |
| NPTF | 1/16"-27 NPTF | 27 TPI | 7.938 | 0.313 | 6.205 | 7.142 | 11/32 (R 0.339" reamer) | 8.45 | 8.95 | Dryseal Taper 1:16 (3/4" per foot). Drill values per Machinery's Handbook. |
| NPTF | 1/8"-27 NPTF | 27 TPI | 10.287 | 0.405 | 8.552 | 8.733 | 11/32 | 10.79 | 11.30 | Dryseal Taper 1:16 (3/4" per foot). Drill values per Machinery's Handbook. |
| NPTF | 1/4"-18 NPTF | 18 TPI | 13.716 | 0.540 | 10.752 | 11.112 | 7/16 | 14.22 | 14.73 | Dryseal Taper 1:16 (3/4" per foot). Drill values per Machinery's Handbook. |
| NPTF | 3/8"-18 NPTF | 18 TPI | 17.145 | 0.675 | 14.420 | 14.684 | 37/64 | 17.65 | 18.16 | Dryseal Taper 1:16 (3/4" per foot). Drill values per Machinery's Handbook. |
| NPTF | 1/2"-14 NPTF | 14 TPI | 21.336 | 0.840 | 17.869 | 17.859 | 45/64 | 21.84 | 22.35 | Dryseal Taper 1:16 (3/4" per foot). Drill values per Machinery's Handbook. |
| NPTF | 3/4"-14 NPTF | 14 TPI | 26.670 | 1.050 | 23.142 | 23.020 | 29/32 | 27.18 | 27.69 | Dryseal Taper 1:16 (3/4" per foot). Drill values per Machinery's Handbook. |
| NPTF | 1"-11.5 NPTF | 11.5 TPI | 33.401 | 1.315 | 29.060 | 28.971 | 1 9/64 | 33.91 | 34.42 | Dryseal Taper 1:16 (3/4" per foot). Drill values per Machinery's Handbook. |
| NPTF | 1 1/4"-11.5 NPTF | 11.5 TPI | 42.164 | 1.660 | 37.785 | 37.704 | 1 31/64 | 42.67 | 43.18 | Dryseal Taper 1:16 (3/4" per foot). Drill values per Machinery's Handbook. |
| NPTF | 1 1/2"-11.5 NPTF | 11.5 TPI | 48.260 | 1.900 | 43.853 | 43.658 | 1 23/32 | 48.77 | 49.28 | Dryseal Taper 1:16 (3/4" per foot). Drill values per Machinery's Handbook. |
| NPTF | 2"-11.5 NPTF | 11.5 TPI | 60.325 | 2.375 | 55.941 | 55.563 | 2 3/16 | 60.83 | 61.34 | Dryseal Taper 1:16 (3/4" per foot). Drill values per Machinery's Handbook. |
| NPTF | 2 1/2"-8 NPTF | 8 TPI | 73.025 | 2.875 | 66.535 | 66.675 | 2 5/8 | 73.53 | 74.04 | Dryseal Taper 1:16 (3/4" per foot). Drill values per Machinery's Handbook. |
| NPTF | 3"-8 NPTF | 8 TPI | 88.900 | 3.500 | 82.311 | 82.550 | 3 1/4 | 89.41 | 89.92 | Dryseal Taper 1:16 (3/4" per foot). Drill values per Machinery's Handbook. |
| NPTF | 4"-8 NPTF | 8 TPI | 114.300 | 4.500 | 107.528 | 107.950 | 4 1/4 | 114.81 | 115.32 | Dryseal Taper 1:16 (3/4" per foot). Drill values per Machinery's Handbook. |
| BSPP | G 1/16 (BSPP) | 28 TPI | 7.729 | 0.304 | 6.452 | 6.599 | 6.6 mm | 8.24 | 8.74 | Class A / B Parallel — sealing via O-ring or bonded seal. |
| BSPP | G 1/8 (BSPP) | 28 TPI | 9.728 | 0.383 | 8.451 | 8.600 | 8.6 mm | 10.24 | 10.74 | Class A / B Parallel — sealing via O-ring or bonded seal. |
| BSPP | G 1/4 (BSPP) | 19 TPI | 13.157 | 0.518 | 11.400 | 11.501 | 11.5 mm | 13.66 | 14.17 | Class A / B Parallel — sealing via O-ring or bonded seal. |
| BSPP | G 3/8 (BSPP) | 19 TPI | 16.662 | 0.656 | 14.905 | 15.001 | 15.0 mm | 17.17 | 17.68 | Class A / B Parallel — sealing via O-ring or bonded seal. |
| BSPP | G 1/2 (BSPP) | 14 TPI | 20.955 | 0.825 | 18.499 | 18.499 | 18.5 mm | 21.46 | 21.97 | Class A / B Parallel — sealing via O-ring or bonded seal. |
| BSPP | G 5/8 (BSPP) | 14 TPI | 22.911 | 0.902 | 20.457 | 20.500 | 20.5 mm | 23.42 | 23.93 | Class A / B Parallel — sealing via O-ring or bonded seal. |
| BSPP | G 3/4 (BSPP) | 14 TPI | 26.441 | 1.041 | 23.990 | 24.000 | 24.0 mm | 26.95 | 27.46 | Class A / B Parallel — sealing via O-ring or bonded seal. |
| BSPP | G 7/8 (BSPP) | 14 TPI | 29.997 | 1.181 | 27.541 | 27.600 | 27.5 mm | 30.50 | 31.01 | Class A / B Parallel — sealing via O-ring or bonded seal. |
| BSPP | G 1 (BSPP) | 11 TPI | 33.249 | 1.309 | 30.119 | 30.300 | 30.5 mm | 33.76 | 34.27 | Class A / B Parallel — sealing via O-ring or bonded seal. |
| BSPP | G 1 1/4 (BSPP) | 11 TPI | 41.910 | 1.650 | 38.801 | 38.999 | 39.0 mm | 42.42 | 42.93 | Class A / B Parallel — sealing via O-ring or bonded seal. |
| BSPP | G 1 1/2 (BSPP) | 11 TPI | 47.803 | 1.882 | 44.681 | 45.001 | 45.0 mm | 48.31 | 48.82 | Class A / B Parallel — sealing via O-ring or bonded seal. |
| BSPP | G 2 (BSPP) | 11 TPI | 59.614 | 2.347 | 56.500 | 56.799 | 56.7 mm | 60.12 | 60.63 | Class A / B Parallel — sealing via O-ring or bonded seal. |
| BSPP | G 2 1/2 (BSPP) | 11 TPI | 75.209 | 2.961 | 72.100 | 72.499 | 72.5 mm | 75.72 | 76.22 | Class A / B Parallel — sealing via O-ring or bonded seal. |
| BSPP | G 3 (BSPP) | 11 TPI | 88.011 | 3.465 | 84.899 | 85.400 | 85.4 mm | 88.52 | 89.03 | Class A / B Parallel — sealing via O-ring or bonded seal. |
| BSPP | G 4 (BSPP) | 11 TPI | 113.045 | 4.451 | 109.941 | 110.500 | 110.5 mm | 113.55 | 114.06 | Class A / B Parallel — sealing via O-ring or bonded seal. |
| BSPT | R 1/16 (BSPT) | 28 TPI | 7.729 | 0.304 | 6.452 | 6.599 | 6.6 mm | 8.24 | 8.74 | ISO 7-1 Taper 1:16. Drill same nominal as BSPP per Machinery's Handbook. |
| BSPT | R 1/8 (BSPT) | 28 TPI | 9.728 | 0.383 | 8.451 | 8.600 | 8.6 mm | 10.24 | 10.74 | ISO 7-1 Taper 1:16. Drill same nominal as BSPP per Machinery's Handbook. |
| BSPT | R 1/4 (BSPT) | 19 TPI | 13.157 | 0.518 | 11.400 | 11.501 | 11.5 mm | 13.66 | 14.17 | ISO 7-1 Taper 1:16. Drill same nominal as BSPP per Machinery's Handbook. |
| BSPT | R 3/8 (BSPT) | 19 TPI | 16.662 | 0.656 | 14.905 | 15.001 | 15.0 mm | 17.17 | 17.68 | ISO 7-1 Taper 1:16. Drill same nominal as BSPP per Machinery's Handbook. |
| BSPT | R 1/2 (BSPT) | 14 TPI | 20.955 | 0.825 | 18.499 | 18.499 | 18.5 mm | 21.46 | 21.97 | ISO 7-1 Taper 1:16. Drill same nominal as BSPP per Machinery's Handbook. |
| BSPT | R 5/8 (BSPT) | 14 TPI | 22.911 | 0.902 | 20.457 | 20.500 | 20.5 mm | 23.42 | 23.93 | ISO 7-1 Taper 1:16. Drill same nominal as BSPP per Machinery's Handbook. |
| BSPT | R 3/4 (BSPT) | 14 TPI | 26.441 | 1.041 | 23.990 | 24.000 | 24.0 mm | 26.95 | 27.46 | ISO 7-1 Taper 1:16. Drill same nominal as BSPP per Machinery's Handbook. |
| BSPT | R 7/8 (BSPT) | 14 TPI | 29.997 | 1.181 | 27.541 | 27.600 | 27.5 mm | 30.50 | 31.01 | ISO 7-1 Taper 1:16. Drill same nominal as BSPP per Machinery's Handbook. |
| BSPT | R 1 (BSPT) | 11 TPI | 33.249 | 1.309 | 30.119 | 30.300 | 30.5 mm | 33.76 | 34.27 | ISO 7-1 Taper 1:16. Drill same nominal as BSPP per Machinery's Handbook. |
| BSPT | R 1 1/4 (BSPT) | 11 TPI | 41.910 | 1.650 | 38.801 | 38.999 | 39.0 mm | 42.42 | 42.93 | ISO 7-1 Taper 1:16. Drill same nominal as BSPP per Machinery's Handbook. |
| BSPT | R 1 1/2 (BSPT) | 11 TPI | 47.803 | 1.882 | 44.681 | 45.001 | 45.0 mm | 48.31 | 48.82 | ISO 7-1 Taper 1:16. Drill same nominal as BSPP per Machinery's Handbook. |
| BSPT | R 2 (BSPT) | 11 TPI | 59.614 | 2.347 | 56.500 | 56.799 | 56.7 mm | 60.12 | 60.63 | ISO 7-1 Taper 1:16. Drill same nominal as BSPP per Machinery's Handbook. |
| BSPT | R 2 1/2 (BSPT) | 11 TPI | 75.209 | 2.961 | 72.100 | 72.499 | 72.5 mm | 75.72 | 76.22 | ISO 7-1 Taper 1:16. Drill same nominal as BSPP per Machinery's Handbook. |
| BSPT | R 3 (BSPT) | 11 TPI | 88.011 | 3.465 | 84.899 | 85.400 | 85.4 mm | 88.52 | 89.03 | ISO 7-1 Taper 1:16. Drill same nominal as BSPP per Machinery's Handbook. |
| BSPT | R 4 (BSPT) | 11 TPI | 113.045 | 4.451 | 109.941 | 110.500 | 110.5 mm | 113.55 | 114.06 | ISO 7-1 Taper 1:16. Drill same nominal as BSPP per Machinery's Handbook. |
| BSW | 1/8" BSW | 40 TPI | 3.175 | 0.125 | 2.362 | 2.380 | 3/32 | 3.56 | 3.94 | BS 84 medium Whitworth 55° thread form. |
| BSW | 3/16" BSW | 24 TPI | 4.762 | 0.187 | 3.406 | 3.571 | 9/64 | 5.14 | 5.53 | BS 84 medium Whitworth 55° thread form. |
| BSW | 1/4" BSW | 20 TPI | 6.350 | 0.250 | 4.724 | 5.001 | 5.0 mm | 6.73 | 7.11 | BS 84 medium Whitworth 55° thread form. |
| BSW | 5/16" BSW | 18 TPI | 7.938 | 0.313 | 6.132 | 6.401 | 6.4 mm | 8.32 | 8.70 | BS 84 medium Whitworth 55° thread form. |
| BSW | 3/8" BSW | 16 TPI | 9.525 | 0.375 | 7.493 | 7.800 | 7.8 mm | 9.91 | 10.29 | BS 84 medium Whitworth 55° thread form. |
| BSW | 7/16" BSW | 14 TPI | 11.112 | 0.437 | 8.788 | 9.200 | 9.2 mm | 11.49 | 11.88 | BS 84 medium Whitworth 55° thread form. |
| BSW | 1/2" BSW | 12 TPI | 12.700 | 0.500 | 9.990 | 10.500 | 10.5 mm | 13.08 | 13.46 | BS 84 medium Whitworth 55° thread form. |
| BSW | 9/16" BSW | 12 TPI | 14.288 | 0.563 | 11.577 | 11.999 | 12.0 mm | 14.67 | 15.05 | BS 84 medium Whitworth 55° thread form. |
| BSW | 5/8" BSW | 11 TPI | 15.875 | 0.625 | 12.918 | 13.500 | 13.5 mm | 16.26 | 16.64 | BS 84 medium Whitworth 55° thread form. |
| BSW | 3/4" BSW | 10 TPI | 19.050 | 0.750 | 15.796 | 16.500 | 16.5 mm | 19.43 | 19.81 | BS 84 medium Whitworth 55° thread form. |
| BSW | 7/8" BSW | 9 TPI | 22.225 | 0.875 | 18.611 | 19.500 | 19.5 mm | 22.61 | 22.99 | BS 84 medium Whitworth 55° thread form. |
| BSW | 1" BSW | 8 TPI | 25.400 | 1.000 | 21.333 | 22.225 | 22.25 mm | 25.78 | 26.16 | BS 84 medium Whitworth 55° thread form. |
| BSW | 1 1/4" BSW | 7 TPI | 31.750 | 1.250 | 27.109 | 28.001 | 28.0 mm | 32.13 | 32.51 | BS 84 medium Whitworth 55° thread form. |
| BSW | 1 1/2" BSW | 6 TPI | 38.100 | 1.500 | 32.680 | 34.000 | 34.0 mm | 38.48 | 38.86 | BS 84 medium Whitworth 55° thread form. |
| BSF | 1/4" BSF | 26 TPI | 6.350 | 0.250 | 5.100 | 5.301 | 5.3 mm | 6.73 | 7.11 | BS 84 medium Whitworth 55° thread form. |
| BSF | 5/16" BSF | 22 TPI | 7.938 | 0.313 | 6.459 | 6.701 | 6.7 mm | 8.32 | 8.70 | BS 84 medium Whitworth 55° thread form. |
| BSF | 3/8" BSF | 20 TPI | 9.525 | 0.375 | 7.899 | 8.199 | 8.2 mm | 9.91 | 10.29 | BS 84 medium Whitworth 55° thread form. |
| BSF | 7/16" BSF | 18 TPI | 11.112 | 0.437 | 9.307 | 9.700 | 9.7 mm | 11.49 | 11.88 | BS 84 medium Whitworth 55° thread form. |
| BSF | 1/2" BSF | 16 TPI | 12.700 | 0.500 | 10.668 | 11.001 | 11.0 mm | 13.08 | 13.46 | BS 84 medium Whitworth 55° thread form. |
| BSF | 9/16" BSF | 16 TPI | 14.288 | 0.563 | 12.256 | 12.601 | 12.6 mm | 14.67 | 15.05 | BS 84 medium Whitworth 55° thread form. |
| BSF | 5/8" BSF | 14 TPI | 15.875 | 0.625 | 13.551 | 14.000 | 14.0 mm | 16.26 | 16.64 | BS 84 medium Whitworth 55° thread form. |
| BSF | 3/4" BSF | 12 TPI | 19.050 | 0.750 | 16.340 | 17.000 | 17.0 mm | 19.43 | 19.81 | BS 84 medium Whitworth 55° thread form. |
| BSF | 7/8" BSF | 11 TPI | 22.225 | 0.875 | 19.268 | 20.000 | 20.0 mm | 22.61 | 22.99 | BS 84 medium Whitworth 55° thread form. |
| BSF | 1" BSF | 10 TPI | 25.400 | 1.000 | 22.146 | 23.000 | 23.0 mm | 25.78 | 26.16 | BS 84 medium Whitworth 55° thread form. |
Parallel threads (ISO-M, UN, BSPP, BSW/BSF): tap drill sized for ~75% thread engagement. Use 65–70% on tougher materials (stainless, titanium, Inconel) to reduce tap breakage. Clearance hole values follow ASME B18.2.8 / ISO 273 (close vs normal fit).
Taper pipe threads (NPT, NPTF, BSPT): taper 1:16 (0.75″/ft). Drill values are recommended pre-tap drill sizes from Machinery's Handbook. NPTF (Dryseal) requires no sealant; NPT/BSPT typically use PTFE tape or thread sealant.
