Helical Coil Thread Inserts Size Chart

 

Thread
Size		 Nominal Length1 Free Outer Diameter Number of Free Coils2
Length of Insert (in Diameter) Nominal Length Diameter
1 1.5 2 2.5 3 Min. Max. 1 1.5 2 2.5 3
Unified Coarse
1-64 0.073 0.110 0.146 0.182 0.219 0.095 0.103 2-3/4 4-7/8 6-7/8 8-7/8 10-7/8
2-56 0.086 0.129 0.172 0.215 0.258 0.110 0.119 3 5-1/4 7-3/8 9-5/8 11-7/8
3-48 0.099 0.148 0.198 0.248 0.297 0.128 0.139 2-7/8 5 7-1/4 9-3/8 11-1/2
4-40 0.112 0.168 0.224 0.280 0.336 0.144 0.159 2-3/4 4-3/4 6-3/4 8-7/8 10-7/8
5-40 0.125 0.188 0.250 0.312 0.375 0.158 0.173 3-1/4 5-1/2 7-3/4 10 12-1/4
6-32 0.138 0.207 0.276 0.345 0.414 0.178 0.193 2-3/4 4-3/4 6-7/8 8-7/8 10-7/8
8-32 0.164 0.246 0.328 0.410 0.492 0.205 0.220 3-1/2 6 8-3/8 10-3/4 13-1/4
10-24 0.190 0.285 0.380 0.475 0.570 0.244 0.259 2-7/8 5 7-1/8 9-1/4 11-3/8
12-24 0.216 0.324 0.432 0.540 0.648 0.270 0.285 3-1/2 6 8-3/8 10-5/8 13-1/8
1/4-20 0.250 0.375 0.500 0.625 0.750 0.310 0.330 3-3/8 5-3/4 8 10-3/8 12-3/4
5/16-18 0.312 0.469 0.625 0.781 0.938 0.380 0.400 4 6-5/8 9-1/4 11-7/8 14-5/8
3/8-16 0.375 0.562 0.750 0.938 1.125 0.452 0.472 4-3/8 7-1/4 10 12-7/8 15-3/4
7/16-14 0.438 0.656 0.875 1.094 1.312 0.526 0.551 4-1/2 7-3/8 10-1/4 13-1/8 16-1/8
1/2-13 0.500 0.750 1.000 1.250 1.500 0.597 0.622 4-7/8 7-7/8 11 14-1/8 17-1/8
9/16-12 0.562 0.844 1.125 1.406 1.688 0.669 0.694 5-1/8 8-1/4 11-1/2 14-3/4 17-7/8
5/8-11 0.625 0.938 1.250 1.562 1.875 0.742 0.767 5-1/4 8-1/2 11-3/4 15 18-3/8
3/4-10 0.750 1.125 1.500 1.875 2.250 0.881 0.906 5-7/8 9-3/8 13 16-1/2 20-1/8
7/8-9 0.875 1.312 1.750 2.188 2.625 1.022 1.052 6-1/4 10 13-3/4 17-1/2 21-1/4
1-8 1.000 1.500 2.000 2.500 3.000 1.166 1.196 6-3/8 10-1/8 14 17-3/4 21-5/8
1-1/8-7 1.125 1.688 2.250 2.812 3.375 1.315 1.355 6-1/8 9-7/8 13-5/8 17-1/2 21-1/4
1-1/4-7 1.250 1.875 2.500 3.125 3.750 1.443 1.483 7 11-1/4 15-3/8 19-1/2 23-3/4
1-3/8-6 1.375 2.062 2.750 3.438 4.125 1.598 1.643 6-1/2 10-1/2 14-3/8 18-3/8 22-1/4
1-1/2-6 1.500 2.250 3.000 3.750 4.500 1.727 1.772 7-1/4 11-1/2 15-7/8 20-1/8 24-1/2
Unified Fine
0-80 0.060 0.090 0.120 — — — — 3 5-1/2 7-3/8 — —
3-56 0.099 0.148 0.198 0.248 0.297 0.131 0.146 3-3/8 5-5/8 8 10-3/8 12-5/8
4-48 0.112 0.168 0.224 0.280 0.336 0.147 0.162 3-3/8 5-5/8 7-7/8 10-1/4 12-1/2
6-40 0.138 0.207 0.276 0.345 0.414 0.173 0.193 3-1/2 6 8-3/8 10-3/4 13-1/4
8-36 0.164 0.246 0.328 0.410 0.492 0.204 0.224 3-7/8 6-1/2 9-1/8 11-5/8 14-1/4
10-32 0.190 0.285 0.380 0.475 0.570 0.236 0.256 4-1/8 6-7/8 9-1/2 12* 14-7/8
1/4-28 0.250 0.375 0.500 0.625 0.750 0.306 0.326 5 8-1/4 11-3/8 14-1/2 17-5/8
5/16-24 0.312 0.469 0.625 0.781 0.938 0.380 0.400 5-1/2 8-7/8 12-1/4 15-5/8 19
3/8-24 0.375 0.562 0.750 0.938 1.125 0.448 0.468 6-7/8 11 15 19-1/8 23-1/8
7/16-20 0.438 0.656 0.875 1.094 1.312 0.524 0.549 6-5/8 10-5/8 14-5/8 18-1/2 22-1/2
1/2-20 0.500 0.750 1.000 1.250 1.500 0.592 0.617 7-7/8 12-3/8 16-7/8 21-3/8 25-7/8
9/16-18 0.562 0.844 1.125 1.406 1.688 0.666 0.691 8 12-1/2 17-1/8 21-3/4 26-1/4
5/8-18 0.625 0.938 1.250 1.562 1.875 0.733 0.758 9 14-1/8 19-1/4 24-1/4 29-3/8
3/4-16 0.750 1.125 1.500 1.875 2.250 0.876 0.901 9-3/4 15-1/8 20-5/8 26 31-1/2
7/8-14 0.875 1.312 1.750 2.188 2.625 1.021 1.051 9-7/8 15-1/2 21-1/8 26-5/8 32-1/4
1-12 1.000 1.500 2.000 2.500 3.000 1.169 1.199 9-5/8 15 20-1/2 26 31-1/2
1-1/8-12 1.125 1.688 2.250 2.812 3.375 1.304 1.334 11-1/8 17-1/4 23-3/8 29-1/2 35-3/4
1-1/4-12 1.250 1.875 2.500 3.125 3.750 1.439 1.469 12-1/2 19-3/8 26-1/4 33 39-7/8
1-3/8-12 1.375 2.062 2.750 3.438 4.125 1.575 1.610 13-3/4 21-3/8 28-7/8 36-1/2 44
1-1/2-12 1.500 2.250 3.000 3.750 4.500 1.710 1.745 15-1/4 23-1/2 31-5/8 39-7/8 48-1/8

Please Note:

  • All dimensions for unified sizes are in inches.
Thread
Size		 Nominal Length1 Free Outer Diameter Number of Free Coils2
Length of Inserts (in Diameter) Nominal Length Diameter
1 1.5 2 2.5 3 Min. Max. 1 1.5 2 2.5 3
Metric Coarse
M2X.4 2.0 3.0 4.0 5.0 6.0 2.50 2.70 3-1/4 5-1/2 7-3/4 10-1/8 12-3/8
M2.2X0.45 2.2 3.3 4.4 5.5 6.6 2.80 3.00 3-1/8 5-3/8 7-5/8 9-7/8 12-1/8
M2.5X0.45 2.5 3.8 5.0 6.3 7.5 3.20 3.70 3-3/8 5-3/4 8-1/8 10-1/2 12-3/4
M3X0.5 3.0 4.5 6.0 7.5 9.0 3.80 4.35 3-3/4 6-3/8 8-7/8 11-3/8 13-7/8
M3.5X0.6 3.5 5.3 7.0 8.8 10.5 4.40 4.95 3-3/4 6-3/8 8-3/4 11-3/8 13-3/4
M4X0.7 4.0 6.0 8.0 10.0 12.0 5.05 5.60 3-5/8 6-1/8 8-5/8 11-1/8 13-5/8
M5X0.8 5.0 7.5 10.0 12.5 15.0 6.25 6.80 4-1/8 6-7/8 9-5/8 12-3/8 15-1/8
M6X1 6.0 9.0 12.0 15.0 18.0 7.40 7.95 4 6-3/4 9-1/2 12-1/8 14-7/8
M7X1 7.0 10.5 14.0 17.5 21.0 8.65 9.20 4-7/8 8 11-1/8 14-1/8 17-1/4
M8X1.25 8.0 12.0 16.0 20.0 24.0 9.80 10.35 4-1/2 7-3/8 10-1/4 13-1/4 16-1/8
M10X1.5 10.0 15.0 20.0 25.0 30.0 11.95 12.50 4-7/8 8 11-1/8 14-1/4 17-3/8
M12X1.75 12.0 18.0 24.0 30.0 36.0 14.30 15.00 5 8-1/4 11-1/2 14-5/8 17-7/8
M14X2 14.0 21.0 28.0 35.0 42.0 16.65 17.35 5-1/8 8-1/2 11-3/4 15 18-3/8
M16X2 16.0 24.0 32.0 40.0 48.0 18.90 19.60 6-1/8 9-3/4 13-1/2 17-1/4 21
M18X2.5 18.0 27.0 36.0 45.0 54.0 21.30 22.00 5-3/8 8-7/8 12-1/4 15-5/8 19
M20X2.5 20.0 30.0 40.0 50.0 60.0 23.55 24.40 6-1/8 9-7/8 13-5/8 17-3/8 21-1/8
M22X2.5 22.0 33.0 44.0 55.0 66.0 25.90 26.90 6-3/4 10-7/8 14-7/8 19 23-1/8
M24X3 24.0 36.0 48.0 60.0 72.0 28.00 29.00 6-1/8 10 13-3/4 17-1/2 21-3/8
M27X3 27.0 40.5 54.0 67.5 81.0 31.40 32.40 7 11-1/4 15-1/2 19-3/4 24
M30X3.5 30.0 45.0 60.0 75.0 90.0 34.80 36.00 6-3/4 10-3/4 14-7/8 18-7/8 23
M33X3.5 33.0 49.5 66.0 82.5 99.0 37.80 39.20 7-1/2 12 16-1/2 21 25-3/8
M36X4 36.0 54.0 72.0 90.0 108.0 41.50 42.90 7-1/8 11-3/8 15-5/8 19-7/8 24-1/4
M39X4 39.0 58.5 78.0 97.5 117.0 44.60 46.00 7-7/8 12-1/2 17-1/8 21-3/4 26-3/8
Metric Fine
M8X1 8.0 12.0 16.0 20.0 24.0 9.70 10.25 5-7/8 9-3/8 13 16-1/2 20-1/8
M10X1 10.0 15.0 20.0 25.0 30.0 11.95 12.50 7-5/8 12 16-1/2 21 25-1/2
M10X1.25 10.0 15.0 20.0 25.0 30.0 12.10 12.65 5-7/8 9-1/2 13-1/8 16-3/4 20-3/8
M12X1.25 12.0 18.0 24.0 30.0 36.0 14.30 15.00 7-1/4 11-5/8 15-7/8 20-1/4 24-1/2
M12X1.5 12.0 18.0 24.0 30.0 36.0 14.25 14.95 6 9-5/8 13-3/8 17 20-3/4
M14X1.5 14.0 21.0 28.0 35.0 42.0 16.55 17.25 7-1/8 11-3/8 15-5/8 20 24-1/4
M16X1.5 16.0 24.0 32.0 40.0 48.0 18.90 19.60 8-1/4 13-1/8 18 22-3/4 27-5/8
M18X1.5 18.0 27.0 36.0 45.0 54.0 21.05 21.75 9-1/2 15 20-3/8 25-7/8 31-3/8
M20X1.5 20.0 30.0 40.0 50.0 60.0 23.15 24.00 10-3/4 16-7/8 22-7/8 28-7/8 35
M22X1.5 22.0 33.0 44.0 55.0 66.0 25.55 26.45 11-7/8 18-1/2 25-1/8 31-5/8 38-1/4
M18X2 18.0 27.0 36.0 45.0 54.0 21.15 21.85 7 11-1/8 15-3/8 19-1/2 23-5/8
M20X2 20.0 30.0 40.0 50.0 60.0 23.20 24.05 7-7/8 12-1/2 17-1/4 27-7/8 26-1/2
M22X2 22.0 33.0 44.0 55.0 66.0 25.60 26.50 8-3/4 13-3/4 18-7/8 23-7/8 29
M24X2 24.0 36.0 48.0 60.0 72.0 28.10 29.10 9-1/2 15 20-3/8 25-7/8 31-3/4
M27X2 27.0 40.5 54.0 67.5 81.0 31.30 32.30 10-7/8 17 23-1/4 29-3/8 35-1/2
M30X2 30.0 45.0 60.0 75.0 90.0 34.50 35.70 12-1/4 19-1/8 25-7/8 32-3/4 39-1/2
M33X2 33.0 49.5 66.0 82.5 99.0 37.80 39.20 13-5/8 21-1/8 28-5/8 36 43-1/2
M36X2 36.0 54.0 72.0 90.0 108.0 41.00 42.40 15 23-1/4 31-3/8 39-1/2 47-3/4
M39X2 39.0 58.5 78.0 97.5 117.0 44.30 45.70 16-3/8 25-1/4 34-1/8 43 51-7/8
M36X3 36.0 54.0 72.0 90.0 108.0 41.30 42.70 9-3/4 15-1/4 20-7/8 26-1/2 32
M39X3 39.0 58.5 78.0 97.5 117.0 44.40 45.80 10-3/4 16-3/4 22-3/4 28-7/8 34-7/8

Please Note:

  • Nominal length is a calculated number and cannot be measured in the free state. It is the actual installed length plus 1/2 pitch.
  • For Tangless CoilThread inserts, the number of free coils is the total number of convolutions (counted from notch to notch) and has a tolerance of ±1/4 coil. For CoilThread (tanged) inserts, the number of free coils is the total number of convolutions and has a tolerance of ±1/4 coil. Convolutions are counted by starting  90° from the tang for all sizes.
  • Tangless inserts are available for select UNC & UNF sizes up to 3/8″, and select metric coarse sizes up to M12.
  • All dimensions for reference only.