Thread size master chart — 180 threads across 13 families
Every thread is identified by two numbers: major (outside) diameter and pitch. Caliper the OD, gauge or count the pitch, and read across. Flank angle decides compatibility — 55° (Whitworth: BSW, BSF, G/R) never mates reliably with 60° (M, UN, NPT), and Pg’s 80° mates with nothing else, even where diameters nearly collide (Pg13.5 at 20.4 mm vs M20; ¼-20 BSW vs ¼-20 UNC). Male threads measure slightly under these nominals. Or skip the chart: type your measurement into the identifier.
M — 60° flank
| Designation | Major Ø (mm) | Major (in) | Pitch (mm) | TPI |
|---|---|---|---|---|
| M1.6×0.35 | 1.60 | 0.063 | 0.350 | 72.57 |
| M2×0.4 | 2.00 | 0.079 | 0.400 | 63.5 |
| M2.5×0.45 | 2.50 | 0.098 | 0.450 | 56.44 |
| M3×0.5 | 3.00 | 0.118 | 0.500 | 50.8 |
| M3.5×0.6 | 3.50 | 0.138 | 0.600 | 42.33 |
| M4×0.7 | 4.00 | 0.157 | 0.700 | 36.29 |
| M5×0.8 | 5.00 | 0.197 | 0.800 | 31.75 |
| M6×1 | 6.00 | 0.236 | 1.000 | 25.4 |
| M7×1 | 7.00 | 0.276 | 1.000 | 25.4 |
| M8×1.25 | 8.00 | 0.315 | 1.250 | 20.32 |
| M10×1.5 | 10.00 | 0.394 | 1.500 | 16.93 |
| M12×1.75 | 12.00 | 0.472 | 1.750 | 14.51 |
| M14×2 | 14.00 | 0.551 | 2.000 | 12.7 |
| M16×2 | 16.00 | 0.630 | 2.000 | 12.7 |
| M18×2.5 | 18.00 | 0.709 | 2.500 | 10.16 |
| M20×2.5 | 20.00 | 0.787 | 2.500 | 10.16 |
| M22×2.5 | 22.00 | 0.866 | 2.500 | 10.16 |
| M24×3 | 24.00 | 0.945 | 3.000 | 8.467 |
| M27×3 | 27.00 | 1.063 | 3.000 | 8.467 |
| M30×3.5 | 30.00 | 1.181 | 3.500 | 7.257 |
| M33×3.5 | 33.00 | 1.299 | 3.500 | 7.257 |
| M36×4 | 36.00 | 1.417 | 4.000 | 6.35 |
| M39×4 | 39.00 | 1.535 | 4.000 | 6.35 |
| M42×4.5 | 42.00 | 1.654 | 4.500 | 5.644 |
| M45×4.5 | 45.00 | 1.772 | 4.500 | 5.644 |
| M48×5 | 48.00 | 1.890 | 5.000 | 5.08 |
| M52×5 | 52.00 | 2.047 | 5.000 | 5.08 |
| M56×5.5 | 56.00 | 2.205 | 5.500 | 4.618 |
| M60×5.5 | 60.00 | 2.362 | 5.500 | 4.618 |
| M64×6 | 64.00 | 2.520 | 6.000 | 4.233 |
M fine — 60° flank
| Designation | Major Ø (mm) | Major (in) | Pitch (mm) | TPI |
|---|---|---|---|---|
| M6×0.75 | 6.00 | 0.236 | 0.750 | 33.87 |
| M8×1 | 8.00 | 0.315 | 1.000 | 25.4 |
| M10×1.25 | 10.00 | 0.394 | 1.250 | 20.32 |
| M10×1 | 10.00 | 0.394 | 1.000 | 25.4 |
| M12×1.5 | 12.00 | 0.472 | 1.500 | 16.93 |
| M12×1.25 | 12.00 | 0.472 | 1.250 | 20.32 |
| M14×1.5 | 14.00 | 0.551 | 1.500 | 16.93 |
| M14×1.25 | 14.00 | 0.551 | 1.250 | 20.32 |
| M16×1.5 | 16.00 | 0.630 | 1.500 | 16.93 |
| M18×1.5 | 18.00 | 0.709 | 1.500 | 16.93 |
| M20×1.5 | 20.00 | 0.787 | 1.500 | 16.93 |
| M20×2 | 20.00 | 0.787 | 2.000 | 12.7 |
| M22×1.5 | 22.00 | 0.866 | 1.500 | 16.93 |
| M24×2 | 24.00 | 0.945 | 2.000 | 12.7 |
| M27×2 | 27.00 | 1.063 | 2.000 | 12.7 |
| M30×2 | 30.00 | 1.181 | 2.000 | 12.7 |
| M33×2 | 33.00 | 1.299 | 2.000 | 12.7 |
| M36×3 | 36.00 | 1.417 | 3.000 | 8.467 |
| M42×3 | 42.00 | 1.654 | 3.000 | 8.467 |
| M48×3 | 48.00 | 1.890 | 3.000 | 8.467 |
UNC — 60° flank
| Designation | Major Ø (mm) | Major (in) | Pitch (mm) | TPI |
|---|---|---|---|---|
| #4-40 | 2.85 | 0.112 | 0.635 | 40 |
| #6-32 | 3.50 | 0.138 | 0.794 | 32 |
| #8-32 | 4.17 | 0.164 | 0.794 | 32 |
| #10-24 | 4.83 | 0.190 | 1.058 | 24 |
| #12-24 | 5.49 | 0.216 | 1.058 | 24 |
| 1/4-20 | 6.35 | 0.250 | 1.270 | 20 |
| 5/16-18 | 7.94 | 0.313 | 1.411 | 18 |
| 3/8-16 | 9.53 | 0.375 | 1.587 | 16 |
| 7/16-14 | 11.11 | 0.437 | 1.814 | 14 |
| 1/2-13 | 12.70 | 0.500 | 1.954 | 13 |
| 9/16-12 | 14.29 | 0.562 | 2.117 | 12 |
| 5/8-11 | 15.88 | 0.625 | 2.309 | 11 |
| 3/4-10 | 19.05 | 0.750 | 2.540 | 10 |
| 7/8-9 | 22.23 | 0.875 | 2.822 | 9 |
| 1-8 | 25.40 | 1.000 | 3.175 | 8 |
| 1 1/8-7 | 28.57 | 1.125 | 3.629 | 7 |
| 1 1/4-7 | 31.75 | 1.250 | 3.629 | 7 |
| 1 3/8-6 | 34.92 | 1.375 | 4.233 | 6 |
| 1 1/2-6 | 38.10 | 1.500 | 4.233 | 6 |
UNF — 60° flank
| Designation | Major Ø (mm) | Major (in) | Pitch (mm) | TPI |
|---|---|---|---|---|
| #4-48 | 2.85 | 0.112 | 0.529 | 48 |
| #6-40 | 3.50 | 0.138 | 0.635 | 40 |
| #8-36 | 4.17 | 0.164 | 0.706 | 36 |
| #10-32 | 4.83 | 0.190 | 0.794 | 32 |
| 1/4-28 | 6.35 | 0.250 | 0.907 | 28 |
| 5/16-24 | 7.94 | 0.313 | 1.058 | 24 |
| 3/8-24 | 9.53 | 0.375 | 1.058 | 24 |
| 7/16-20 | 11.11 | 0.437 | 1.270 | 20 |
| 1/2-20 | 12.70 | 0.500 | 1.270 | 20 |
| 9/16-18 | 14.29 | 0.562 | 1.411 | 18 |
| 5/8-18 | 15.88 | 0.625 | 1.411 | 18 |
| 3/4-16 | 19.05 | 0.750 | 1.587 | 16 |
| 7/8-14 | 22.23 | 0.875 | 1.814 | 14 |
| 1-12 | 25.40 | 1.000 | 2.117 | 12 |
| 1 1/8-12 | 28.57 | 1.125 | 2.117 | 12 |
| 1 1/4-12 | 31.75 | 1.250 | 2.117 | 12 |
| 1 1/2-12 | 38.10 | 1.500 | 2.117 | 12 |
UNEF — 60° flank
| Designation | Major Ø (mm) | Major (in) | Pitch (mm) | TPI |
|---|---|---|---|---|
| 1/4-32 | 6.35 | 0.250 | 0.794 | 32 |
| 5/16-32 | 7.94 | 0.313 | 0.794 | 32 |
| 3/8-32 | 9.53 | 0.375 | 0.794 | 32 |
| 7/16-28 | 11.11 | 0.437 | 0.907 | 28 |
| 1/2-28 | 12.70 | 0.500 | 0.907 | 28 |
| 9/16-24 | 14.29 | 0.562 | 1.058 | 24 |
| 5/8-24 | 15.88 | 0.625 | 1.058 | 24 |
| 5/8-27 | 15.88 | 0.625 | 0.941 | 27 |
| 11/16-24 | 17.46 | 0.687 | 1.058 | 24 |
| 3/4-20 | 19.05 | 0.750 | 1.270 | 20 |
| 7/8-20 | 22.23 | 0.875 | 1.270 | 20 |
| 1-20 | 25.40 | 1.000 | 1.270 | 20 |
BSW — 55° flank
| Designation | Major Ø (mm) | Major (in) | Pitch (mm) | TPI |
|---|---|---|---|---|
| 1/8-40 | 3.17 | 0.125 | 0.635 | 40 |
| 3/16-24 | 4.76 | 0.187 | 1.058 | 24 |
| 1/4-20 | 6.35 | 0.250 | 1.270 | 20 |
| 5/16-18 | 7.94 | 0.313 | 1.411 | 18 |
| 3/8-16 | 9.53 | 0.375 | 1.587 | 16 |
| 7/16-14 | 11.11 | 0.437 | 1.814 | 14 |
| 1/2-12 | 12.70 | 0.500 | 2.117 | 12 |
| 9/16-12 | 14.29 | 0.562 | 2.117 | 12 |
| 5/8-11 | 15.88 | 0.625 | 2.309 | 11 |
| 3/4-10 | 19.05 | 0.750 | 2.540 | 10 |
| 7/8-9 | 22.23 | 0.875 | 2.822 | 9 |
| 1-8 | 25.40 | 1.000 | 3.175 | 8 |
BSF — 55° flank
| Designation | Major Ø (mm) | Major (in) | Pitch (mm) | TPI |
|---|---|---|---|---|
| 1/4-26 | 6.35 | 0.250 | 0.977 | 26 |
| 5/16-22 | 7.94 | 0.313 | 1.155 | 22 |
| 3/8-20 | 9.53 | 0.375 | 1.270 | 20 |
| 7/16-18 | 11.11 | 0.437 | 1.411 | 18 |
| 1/2-16 | 12.70 | 0.500 | 1.587 | 16 |
| 9/16-16 | 14.29 | 0.562 | 1.587 | 16 |
| 5/8-14 | 15.88 | 0.625 | 1.814 | 14 |
| 3/4-12 | 19.05 | 0.750 | 2.117 | 12 |
| 7/8-11 | 22.23 | 0.875 | 2.309 | 11 |
| 1-10 | 25.40 | 1.000 | 2.540 | 10 |
BA — 47.5° flank
| Designation | Major Ø (mm) | Major (in) | Pitch (mm) | TPI |
|---|---|---|---|---|
| 0BA | 6.00 | 0.236 | 1.000 | 25.4 |
| 1BA | 5.30 | 0.209 | 0.900 | 28.22 |
| 2BA | 4.70 | 0.185 | 0.810 | 31.36 |
| 3BA | 4.10 | 0.161 | 0.730 | 34.79 |
| 4BA | 3.60 | 0.142 | 0.660 | 38.48 |
| 5BA | 3.20 | 0.126 | 0.590 | 43.05 |
| 6BA | 2.80 | 0.110 | 0.530 | 47.92 |
| 8BA | 2.20 | 0.087 | 0.430 | 59.07 |
| 10BA | 1.70 | 0.067 | 0.350 | 72.57 |
G/R — 55° flank
| Designation | Major Ø (mm) | Major (in) | Pitch (mm) | TPI |
|---|---|---|---|---|
| G 1/8 | 9.73 | 0.383 | 0.907 | 28 |
| G 1/4 | 13.16 | 0.518 | 1.337 | 19 |
| G 3/8 | 16.66 | 0.656 | 1.337 | 19 |
| G 1/2 | 20.95 | 0.825 | 1.814 | 14 |
| G 3/4 | 26.44 | 1.041 | 1.814 | 14 |
| G 1 | 33.25 | 1.309 | 2.309 | 11 |
| G 1 1/4 | 41.91 | 1.650 | 2.309 | 11 |
| G 1 1/2 | 47.80 | 1.882 | 2.309 | 11 |
| G 2 | 59.61 | 2.347 | 2.309 | 11 |
| G 2 1/2 | 75.18 | 2.960 | 2.309 | 11 |
| G 3 | 87.88 | 3.460 | 2.309 | 11 |
NPT — 60° flank
| Designation | Major Ø (mm) | Major (in) | Pitch (mm) | TPI |
|---|---|---|---|---|
| 1/8 | 10.29 | 0.405 | 0.941 | 27 |
| 1/4 | 13.72 | 0.540 | 1.411 | 18 |
| 3/8 | 17.14 | 0.675 | 1.411 | 18 |
| 1/2 | 21.34 | 0.840 | 1.814 | 14 |
| 3/4 | 26.67 | 1.050 | 1.814 | 14 |
| 1 | 33.40 | 1.315 | 2.209 | 11.5 |
| 1 1/4 | 42.16 | 1.660 | 2.209 | 11.5 |
| 1 1/2 | 48.26 | 1.900 | 2.209 | 11.5 |
| 2 | 60.33 | 2.375 | 2.209 | 11.5 |
Pg — 80° flank
| Designation | Major Ø (mm) | Major (in) | Pitch (mm) | TPI |
|---|---|---|---|---|
| Pg7 | 12.50 | 0.492 | 1.270 | 20 |
| Pg9 | 15.20 | 0.598 | 1.411 | 18 |
| Pg11 | 18.60 | 0.732 | 1.411 | 18 |
| Pg13.5 | 20.40 | 0.803 | 1.411 | 18 |
| Pg16 | 22.50 | 0.886 | 1.411 | 18 |
| Pg21 | 28.30 | 1.114 | 1.587 | 16 |
| Pg29 | 37.00 | 1.457 | 1.587 | 16 |
| Pg36 | 47.00 | 1.850 | 1.587 | 16 |
| Pg42 | 54.00 | 2.126 | 1.587 | 16 |
| Pg48 | 59.30 | 2.335 | 1.587 | 16 |
Tr — 30° flank
| Designation | Major Ø (mm) | Major (in) | Pitch (mm) | TPI |
|---|---|---|---|---|
| Tr8×1.5 | 8.00 | 0.315 | 1.500 | 16.93 |
| Tr10×2 | 10.00 | 0.394 | 2.000 | 12.7 |
| Tr12×3 | 12.00 | 0.472 | 3.000 | 8.467 |
| Tr16×4 | 16.00 | 0.630 | 4.000 | 6.35 |
| Tr20×4 | 20.00 | 0.787 | 4.000 | 6.35 |
| Tr24×5 | 24.00 | 0.945 | 5.000 | 5.08 |
| Tr28×5 | 28.00 | 1.102 | 5.000 | 5.08 |
| Tr32×6 | 32.00 | 1.260 | 6.000 | 4.233 |
| Tr36×6 | 36.00 | 1.417 | 6.000 | 4.233 |
| Tr40×7 | 40.00 | 1.575 | 7.000 | 3.629 |
| Tr44×7 | 44.00 | 1.732 | 7.000 | 3.629 |
| Tr48×8 | 48.00 | 1.890 | 8.000 | 3.175 |
ACME — 29° flank
| Designation | Major Ø (mm) | Major (in) | Pitch (mm) | TPI |
|---|---|---|---|---|
| 1/4-16 | 6.35 | 0.250 | 1.587 | 16 |
| 5/16-14 | 7.94 | 0.313 | 1.814 | 14 |
| 3/8-12 | 9.53 | 0.375 | 2.117 | 12 |
| 1/2-10 | 12.70 | 0.500 | 2.540 | 10 |
| 5/8-8 | 15.88 | 0.625 | 3.175 | 8 |
| 3/4-6 | 19.05 | 0.750 | 4.233 | 6 |
| 1-5 | 25.40 | 1.000 | 5.080 | 5 |
| 1 1/4-5 | 31.75 | 1.250 | 5.080 | 5 |
| 1 1/2-4 | 38.10 | 1.500 | 6.350 | 4 |
Sources: ISO 261/262 (metric), ASME B1.1 (UN), BS 84/93 (BSW/BSF/BA), ISO 228 & ISO 7 (G/R), ASME B1.20.1 (NPT), DIN 40430 (Pg), ISO 2903 (Tr), ASME B1.5 (ACME). Values are nominal.