Thread Reference (India Common Threads)
Metric Threads (MM)
| Thread Name | Standard | Major Dia (mm) | Minor Dia (mm) | Pitch (mm) | TPI | Drill Size (mm) | Drill Size (inch) | Description |
|---|---|---|---|---|---|---|---|---|
| M1 | ISO Metric | 1 | 0.75 | 0.25 | - | 0.75 | 0.030" | Micro screws |
| M1.1 | ISO Metric | 1.1 | 0.85 | 0.25 | - | 0.85 | 0.033" | Micro screws |
| M1.2 | ISO Metric | 1.2 | 0.95 | 0.25 | - | 0.95 | 0.037" | Micro screws |
| M1.4 | ISO Metric | 1.4 | 1.075 | 0.3 | - | 1.075 | 0.042" | Small screws |
| M1.6 | ISO Metric | 1.6 | 1.221 | 0.35 | - | 1.221 | 0.048" | Small screws |
| M1.8 | ISO Metric | 1.8 | 1.421 | 0.35 | - | 1.421 | 0.056" | Small bolts |
| M2 | ISO Metric | 2 | 1.567 | 0.4 | - | 1.567 | 0.062" | General small bolts |
| M2.2 | ISO Metric | 2.2 | 1.713 | 0.45 | - | 1.713 | 0.067" | Small screws |
| M2.5 | ISO Metric | 2.5 | 2.013 | 0.45 | - | 2.013 | 0.079" | Small bolts |
| M3 | ISO Metric | 3 | 2.459 | 0.5 | - | 2.459 | 0.097" | General purpose small screw |
| M3.5 | ISO Metric | 3.5 | 2.85 | 0.6 | - | 2.85 | 0.112" | Medium screws |
| M4 | ISO Metric | 4 | 3.242 | 0.7 | - | 3.242 | 0.128" | Machine screws, common in India |
| M4.5 | ISO Metric | 4.5 | 3.688 | 0.75 | - | 3.688 | 0.145" | Medium screws |
| M5 | ISO Metric | 5 | 4.134 | 0.8 | - | 4.134 | 0.163" | Medium bolts |
| M6 | ISO Metric | 6 | 4.917 | 1.0 | - | 4.917 | 0.194" | Heavy machinery |
| M7 | ISO Metric | 7 | 5.917 | 1.0 | - | 5.917 | 0.233" | Medium bolts |
| M8 | ISO Metric | 8 | 6.647 | 1.25 | - | 6.647 | 0.261" | Bolts and nuts |
| M9 | ISO Metric | 9 | 7.647 | 1.25 | - | 7.647 | 0.301" | Medium bolts |
| M10 | ISO Metric | 10 | 8.376 | 1.5 | - | 8.376 | 0.330" | Medium industrial bolts |
| M11 | ISO Metric | 11 | 9.376 | 1.5 | - | 9.376 | 0.369" | Heavy bolts |
| M12 | ISO Metric | 12 | 10.106 | 1.75 | - | 10.106 | 0.398" | Heavy industrial bolts |
| M14 | ISO Metric | 14 | 11.835 | 2.0 | - | 11.835 | 0.466" | Structural bolts |
| M16 | ISO Metric | 16 | 13.835 | 2.0 | - | 13.835 | 0.545" | Heavy equipment bolts |
| M18 | ISO Metric | 18 | 15.394 | 2.5 | - | 15.394 | 0.606" | Large machinery bolts |
| M20 | ISO Metric | 20 | 17.294 | 2.5 | - | 17.294 | 0.681" | Heavy industrial bolts |
| M22 | ISO Metric | 22 | 19.294 | 2.5 | - | 19.294 | 0.759" | Industrial bolts |
| M24 | ISO Metric | 24 | 20.752 | 3.0 | - | 20.752 | 0.817" | Heavy industrial bolts |
| M27 | ISO Metric | 27 | 23.752 | 3.0 | - | 23.752 | 0.935" | Large structural bolts |
| M30 | ISO Metric | 30 | 26.211 | 3.5 | - | 26.211 | 1.032" | Heavy industrial |
| M33 | ISO Metric | 33 | 29.211 | 3.5 | - | 29.211 | 1.150" | Heavy machinery |
| M36 | ISO Metric | 36 | 31.67 | 4.0 | - | 31.67 | 1.247" | Large bolts |
| M39 | ISO Metric | 39 | 34.67 | 4.0 | - | 34.67 | 1.366" | Structural bolts |
| M42 | ISO Metric | 42 | 37.129 | 4.5 | - | 37.129 | 1.460" | Heavy industrial bolts |
| M48 | ISO Metric | 48 | 42.857 | 5.0 | - | 42.857 | 1.686" | Large bolts |
| M52 | ISO Metric | 52 | 46.587 | 5.0 | - | 46.587 | 1.835" | Industrial bolts |
| M56 | ISO Metric | 56 | 50.046 | 5.5 | - | 50.046 | 1.968" | Heavy bolts |
| M60 | ISO Metric | 60 | 54.046 | 5.5 | - | 54.046 | 2.126" | Industrial fasteners |
| M64 | ISO Metric | 64 | 57.505 | 6.0 | - | 57.505 | 2.263" | Heavy machinery |
| M68 | ISO Metric | 68 | 61.505 | 6.0 | - | 61.505 | 2.422" | Large bolts |
BSW Threads
| Thread Name | Standard | Major Dia (mm) | Minor Dia (mm) | Pitch (mm) | TPI | Drill Size (mm) | Drill Size (inch) | Description |
|---|---|---|---|---|---|---|---|---|
| 1/16 BSW | BSW | 1.59 | 1.05 | 0.423 | 60 | 1.99 | 0.078" | Miniature fixtures |
| 3/32 BSW | BSW | 2.38 | 1.70 | 0.529 | 48 | 2.67 | 0.105" | Small machinery |
| 1/8 BSW | BSW | 3.18 | 2.36 | 0.635 | 40 | 3.57 | 0.140" | Small bolts / screws |
| 5/32 BSW | BSW | 3.97 | 2.95 | 0.794 | 32 | 4.37 | 0.172" | Workshop fasteners |
| 3/16 BSW | BSW | 4.75 | 3.40 | 1.058 | 24 | 5.16 | 0.203" | Small machine screws |
| 7/32 BSW | BSW | 5.60 | 4.22 | 1.058 | 24 | 5.95 | 0.234" | Workshop bolts |
| 1/4 BSW | BSW | 6.35 | 4.72 | 1.27 | 20 | 6.75 | 0.266" | General machinery |
| 5/16 BSW | BSW | 7.92 | 6.12 | 1.411 | 18 | 8.33 | 0.328" | Medium bolts |
| 3/8 BSW | BSW | 9.53 | 7.49 | 1.588 | 16 | 9.92 | 0.390" | Heavy bolts |
| 7/16 BSW | BSW | 11.10 | 8.79 | 1.814 | 14 | 11.51 | 0.453" | Industrial fasteners |
| 1/2 BSW | BSW | 12.70 | 9.98 | 2.117 | 12 | 13.49 | 0.531" | Large machinery |
| 9/16 BSW | BSW | 14.29 | 11.58 | 2.117 | 12 | 15.08 | 0.594" | Heavy fasteners |
| 5/8 BSW | BSW | 15.88 | 12.93 | 2.309 | 11 | 16.67 | 0.656" | Industrial bolts |
| 11/16 BSW | BSW | 17.48 | 14.50 | 2.309 | 11 | 17.75 | 0.699" | Heavy machinery bolts |
| 3/4 BSW | BSW | 19.05 | 15.80 | 2.540 | 10 | 19.84 | 0.781" | Industrial applications |
| 13/16 BSW | BSW | 20.65 | 17.37 | 2.540 | 10 | 21.00 | 0.827" | Heavy-duty screws |
| 7/8 BSW | BSW | 22.23 | 18.62 | 2.822 | 9 | 23.02 | 0.906" | Large fasteners |
| 15/16 BSW | BSW | 23.83 | 20.19 | 2.822 | 9 | 24.00 | 0.945" | Industrial bolts |
| 1 BSW | BSW | 25.40 | 21.34 | 3.175 | 8 | 26.99 | 1.063" | Heavy machinery |
| 1 1/8 BSW | BSW | 28.58 | 23.93 | 3.629 | 7 | 30.16 | 1.187" | Large bolts |
| 1 1/4 BSW | BSW | 31.75 | 27.10 | 3.629 | 7 | 33.34 | 1.312" | Heavy fasteners |
| 1 3/8 BSW | BSW | 34.93 | 29.51 | 4.233 | 6 | 36.51 | 1.437" | Industrial bolts |
| 1 1/2 BSW | BSW | 38.10 | 32.69 | 4.233 | 6 | 39.69 | 1.562" | Heavy machinery bolts |
| 1 5/8 BSW | BSW | 41.28 | 34.77 | 5.080 | 5 | 41.50 | 1.635" | Large fasteners |
| 1 3/4 BSW | BSW | 44.45 | 37.95 | 5.080 | 5 | 45.00 | 1.772" | Heavy bolts |
| 1 7/8 BSW | BSW | 47.63 | 40.40 | 5.644 | 4.5 | 48.00 | 1.890" | Industrial applications |
| 2 BSW | BSW | 50.80 | 43.57 | 5.644 | 4.5 | 51.00 | 2.008" | Very large bolts |
| 2 1/4 BSW | BSW | 57.15 | 49.38 | 6.350 | 4 | 57.50 | 2.264" | Special heavy-duty |
UNC Threads
| Thread Name | TPI | Major Dia (inch) | Major Dia (mm) | Pitch (inch) | Pitch (mm) | Drill Size (inch) | Drill Size (mm) | Notes |
|---|---|---|---|---|---|---|---|---|
| 1/4 UNC | 20 | 0.2500 | 6.35 | 0.0500 | 1.27 | 0.255" | 6.48 | General purpose coarse thread |
| 5/16 UNC | 18 | 0.3125 | 7.94 | 0.0556 | 1.41 | 0.330" | 8.38 | Industrial fasteners |
| 3/8 UNC | 16 | 0.3750 | 9.53 | 0.0625 | 1.587 | 0.394" | 10.00 | Medium machinery |
| 7/16 UNC | 14 | 0.4375 | 11.11 | 0.0714 | 1.814 | 0.462" | 11.74 | Heavy fittings |
| 1/2 UNC | 13 | 0.5000 | 12.70 | 0.0769 | 1.954 | 0.421" | 10.69 | General bolts |
| 9/16 UNC | 12 | 0.5625 | 14.29 | 0.0833 | 2.116 | 0.484" | 12.29 | Heavy machinery |
| 5/8 UNC | 11 | 0.6250 | 15.88 | 0.0909 | 2.31 | 0.546" | 13.86 | Industrial bolts |
| 3/4 UNC | 10 | 0.7500 | 19.05 | 0.1000 | 2.54 | 0.622" | 15.80 | Heavy machinery |
| 7/8 UNC | 9 | 0.8750 | 22.23 | 0.1111 | 2.82 | 0.733" | 18.62 | Industrial bolts |
| 1 UNC | 8 | 1.0000 | 25.40 | 0.1250 | 3.175 | 0.840" | 21.34 | Large bolts |
| 1 1/8 UNC | 7 | 1.1250 | 28.58 | 0.1429 | 3.63 | 0.942" | 23.91 | Industrial fasteners |
| 1 1/4 UNC | 7 | 1.2500 | 31.75 | 0.1429 | 3.63 | 1.067" | 27.10 | Heavy machinery |
| 1 3/8 UNC | 6 | 1.3750 | 34.93 | 0.1667 | 4.23 | 1.162" | 29.51 | Industrial bolts |
| 1 1/2 UNC | 6 | 1.5000 | 38.10 | 0.1667 | 4.23 | 1.287" | 32.69 | Large bolts |
| 1 5/8 UNC | 5 | 1.6250 | 41.28 | 0.2000 | 5.08 | 1.369" | 34.77 | Heavy machinery |
| 1 3/4 UNC | 5 | 1.7500 | 44.45 | 0.2000 | 5.08 | 45.00 | Industrial bolts | |
| 1 7/8 UNC | 4.5 | 1.8750 | 47.63 | 0.2222 | 5.64 | 48.00 | Large bolts | |
| 2 UNC | 4.5 | 2.0000 | 50.80 | 0.2222 | 5.64 | 51.00 | Heavy industrial |
UNF Threads
| Thread Name | TPI | Major Dia (inch) | Major Dia (mm) | Pitch (inch) | Pitch (mm) | Drill Size (inch) | Drill Size (mm) | Notes |
|---|---|---|---|---|---|---|---|---|
| 1/4 UNF | 28 | 0.2500 | 6.35 | 0.0357 | 0.907 | 0.201" | 5.10 | Fine machine screw |
| 5/16 UNF | 24 | 0.3125 | 7.94 | 0.0417 | 1.06 | 0.268" | 6.80 | Instrument screws |
| 3/8 UNF | 24 | 0.3750 | 9.53 | 0.0417 | 1.06 | 0.299" | 7.60 | Fine thread bolts |
| 7/16 UNF | 20 | 0.4375 | 11.11 | 0.0500 | 1.27 | 0.375" | 9.53 | Machine fasteners |
| 1/2 UNF | 20 | 0.5000 | 12.70 | 0.0500 | 1.27 | 0.421" | 10.70 | Fine machine bolt |
| 9/16 UNF | 18 | 0.5625 | 14.29 | 0.0556 | 1.41 | 0.484" | 12.29 | Industrial fasteners |
| 5/8 UNF | 18 | 0.6250 | 15.88 | 0.0556 | 1.41 | 0.546" | 13.86 | Heavy machinery |
| 3/4 UNF | 16 | 0.7500 | 19.05 | 0.0625 | 1.587 | 0.622" | 15.80 | Machine tools |
| 7/8 UNF | 14 | 0.8750 | 22.23 | 0.0714 | 1.814 | 0.733" | 18.62 | Heavy industrial |
| 1 UNF | 12 | 1.0000 | 25.40 | 0.0833 | 2.116 | 0.840" | 21.34 | Large bolts |
BSP Threads
| Thread Name | Standard | Major Dia (inch) | Major Dia (mm) | Pitch (inch) | Pitch (mm) | Drill Size (inch) | Drill Size (mm) | Notes |
|---|---|---|---|---|---|---|---|---|
| 1/16 BSP | BSP | 0.0620 | 1.59 | 0.0410 | 1.04 | - | 1.99 | Small fluid fittings |
| 1/8 BSP | BSP | 0.1250 | 3.18 | 0.0930 | 2.36 | 9/64" | 3.57 | Instrumentation |
| 1/4 BSP | BSP | 0.2500 | 6.35 | 0.1860 | 4.72 | 17/64" | 6.75 | Plumbing / fluid fittings |
| 3/8 BSP | BSP | 0.3750 | 9.53 | 0.2950 | 7.49 | 25/64" | 9.92 | Industrial pipelines |
| 1/2 BSP | BSP | 0.5000 | 12.70 | 0.3930 | 9.98 | 17/32" | 13.49 | Water / gas pipelines |
| 3/4 BSP | BSP | 0.7500 | 19.05 | 0.6220 | 15.80 | 25/32" | 19.84 | Large industrial fittings |
| 1 BSP | BSP | 1.0000 | 25.40 | 0.8400 | 21.34 | 1 1/16" | 26.99 | Pipelines, valves |
| 1 1/4 BSP | BSP | 1.2500 | 31.75 | 1.0670 | 27.10 | 1 5/16" | 33.34 | Large fluid / gas fittings |
| 1 1/2 BSP | BSP | 1.5000 | 38.10 | 1.2870 | 32.69 | 1 9/16" | 39.69 | Industrial pipelines |
| 2 BSP | BSP | 2.0000 | 50.80 | 1.7150 | 43.57 | - | 51.00 | Large water / gas fittings |
NPT Threads
| Thread Name | Standard | Major Dia (inch) | Major Dia (mm) | Pitch (inch) | Pitch (mm) | Drill Size (inch) | Drill Size (mm) | Notes |
|---|---|---|---|---|---|---|---|---|
| 1/16 NPT | NPT | 0.0625 | 1.59 | 0.0310 | 0.79 | - | 1.98 | Small pneumatic fittings |
| 1/8 NPT | NPT | 0.1250 | 3.18 | 0.0540 | 1.37 | 3/64" | 1.19 | Instrumentation / small pipe |
| 1/4 NPT | NPT | 0.2500 | 6.35 | 0.1410 | 3.58 | 11/64" | 4.37 | Fluid / pneumatic pipelines |
| 3/8 NPT | NPT | 0.3750 | 9.53 | 0.1410 | 3.58 | 7/32" | 5.56 | Small industrial pipelines |
| 1/2 NPT | NPT | 0.5000 | 12.70 | 0.1090 | 2.77 | 15/64" | 5.95 | Gas / water pipe threads |
| 3/4 NPT | NPT | 0.7500 | 19.05 | 0.1560 | 3.96 | 25/64" | 9.92 | Pipelines, industrial |
| 1 NPT | NPT | 1.0000 | 25.40 | 0.1250 | 3.18 | 1 1/16" | 26.99 | Water / gas pipe connections |
| 1 1/4 NPT | NPT | 1.2500 | 31.75 | 0.1250 | 3.18 | 1 5/16" | 33.34 | Industrial pipe threads |
| 1 1/2 NPT | NPT | 1.5000 | 38.10 | 0.1250 | 3.18 | 1 9/16" | 39.69 | Heavy pipelines |
| 2 NPT | NPT | 2.0000 | 50.80 | 0.1250 | 3.18 | 2 1/16" | 52.38 | Large industrial pipelines |
ACME Threads
| Thread Name | Standard | Major Dia (inch) | Major Dia (mm) | Pitch (inch) | Pitch (mm) | TPI | Drill Size (inch) | Drill Size (mm) | Notes |
|---|---|---|---|---|---|---|---|---|---|
| 1/2-10 ACME | ACME | 0.500 | 12.70 | 0.100 | 2.54 | 10 | 0.402 | 10.2 | Power screws, linear motion |
| 3/4-6 ACME | ACME | 0.750 | 19.05 | 0.167 | 4.233 | 6 | 0.610 | 15.5 | Machine tools, vises |
| 1-5 ACME | ACME | 1.000 | 25.40 | 0.200 | 5.08 | 5 | 0.790 | 20.1 | Heavy power screws |
| 1-4 ACME | ACME | 1.000 | 25.40 | 0.250 | 6.35 | 4 | 0.940 | 23.88 | Lead screws, industrial |
| 1 1/4-5 ACME | ACME | 1.250 | 31.75 | 0.200 | 5.08 | 5 | 1.020 | 25.91 | Machine tables, vises |
| 1 1/2-4 ACME | ACME | 1.500 | 38.10 | 0.250 | 6.35 | 4 | 1.250 | 31.75 | Heavy duty power screws |
Trapezoidal TR Threads
| Thread Name | Standard | Major Dia (mm) | Minor Dia (mm) | Pitch (mm) | TPI | Drill Size (mm) | Drill Size (inch) | Description |
|---|---|---|---|---|---|---|---|---|
| TR 12×3 | Trapezoidal | 12 | 9.8 | 3 | - | 9.8 | 0.386" | Lead screws, linear motion |
| TR 16×4 | Trapezoidal | 16 | 12.5 | 4 | - | 12.5 | 0.492" | Industrial vises, machine slides |
| TR 20×4 | Trapezoidal | 20 | 16 | 4 | - | 16 | 0.630" | Machine tools |
| TR 25×5 | Trapezoidal | 25 | 20 | 5 | - | 20 | 0.787" | Heavy equipment, vises |
| TR 30×6 | Trapezoidal | 30 | 24 | 6 | - | 24 | 0.945" | Industrial power screws |
| TR 36×6 | Trapezoidal | 36 | 29 | 6 | - | 29 | 1.142" | Heavy duty linear motion |
BA Threads
| Thread Name | Standard | Major Dia (mm) | Minor Dia (mm) | Pitch (mm) | TPI | Drill Size (mm) | Drill Size (inch) | Description |
|---|---|---|---|---|---|---|---|---|
| 0BA | BA | 6.553 | 5.544 | 1.397 | - | 5.54 | 0.218" | Large electrical fittings |
| 1BA | BA | 5.828 | 4.867 | 1.181 | - | 4.87 | 0.192" | Medium electrical components |
| 2BA | BA | 4.70 | 3.8 | 0.81 | - | 3.8 | 0.150" | Electrical fittings, instrumentation |
| 3BA | BA | 4.14 | 3.34 | 0.69 | - | 3.34 | 0.131" | Small screws, instruments |
| 4BA | BA | 3.64 | 3.0 | 0.65 | - | 3.0 | 0.118" | Old machinery, delicate screws |
| 5BA | BA | 3.30 | 2.66 | 0.55 | - | 2.66 | 0.105" | Miniature instruments |
| 6BA | BA | 2.91 | 2.33 | 0.50 | - | 2.33 | 0.092" | Micro screws, delicate instruments |