|
|
External Thread /Internal Thread |
|
Nominal Size, TPI, Series |
Class |
Allowance |
Maxa Major Max Minor |
Min Major Min Minor |
Min b |
Maxa Pitch |
Min Pitch |
UNRc Minor Dia Major Dia(Min) |
Ext. |
5/16-18 UNC |
1A |
0.0012 |
0.3113 |
0.2982 |
- |
0.2752 |
0.2691 |
0.2452 |
Int. |
|
1B |
|
0.2650 |
0.2520 |
|
0.2843 |
0.2764 |
0.3125 |
Ext. |
5/16-18 UNC |
2A |
0.0012 |
0.3113 |
0.3026 |
0.2982 |
0.2752 |
0.2712 |
0.2452 |
Int. |
|
2B |
|
0.2650 |
0.2520 |
|
0.2817 |
0.2764 |
0.3125 |
Ext. |
5/16-18 UNC |
3A |
0.0000 |
0.3125 |
0.3038 |
- |
0.2764 |
0.2734 |
0.2464 |
Int. |
|
3B |
|
0.2630 |
0.2520 |
|
0.2803 |
0.2764 |
0.3125 |
Ext. |
5/16-20 UN |
2A |
0.0012 |
0.3113 |
0.3032 |
- |
0.2788 |
0.2748 |
0.2518 |
Int. |
|
2B |
|
0.2700 |
0.2580 |
|
0.2852 |
0.2800 |
0.3125 |
Ext. |
5/16-20 UN |
3A |
0.0000 |
0.3125 |
0.3044 |
- |
0.2800 |
0.2770 |
0.2530 |
Int. |
|
3B |
|
0.2680 |
0.2580 |
|
0.2839 |
0.2800 |
0.3125 |
Ext. |
5/16-24 UNF |
1A |
0.0011 |
0.3114 |
0.3006 |
- |
0.2843 |
0.2788 |
0.2618 |
Int. |
|
1B |
|
0.2770 |
0.2670 |
|
0.2925 |
0.2854 |
0.3125 |
Ext. |
5/16-24 UNF |
2A |
0.0011 |
0.3114 |
0.3042 |
- |
0.2843 |
0.2806 |
0.2618 |
Int. |
|
2B |
|
0.2770 |
0.2670 |
|
0.2902 |
0.2854 |
0.3125 |
Ext. |
5/16-24 UNF |
3A |
0.0000 |
0.3125 |
0.3053 |
- |
0.2854 |
0.2827 |
0.2629 |
Int. |
|
3B |
|
0.2754 |
0.2670 |
|
0.2890 |
0.2854 |
0.3125 |
Ext. |
5/16-27 UNS |
2A |
0.0010 |
0.3115 |
0.3048 |
- |
0.2874 |
0.2839 |
0.2674 |
Int. |
|
2B |
|
0.2810 |
0.2720 |
|
0.2929 |
0.2884 |
0.3125 |
Ext. |
5/16-28 UN |
2A |
0.0010 |
0.3115 |
0.3050 |
- |
0.2883 |
0.2849 |
0.2689 |
Int. |
|
2B |
|
0.2820 |
0.2740 |
|
0.2937 |
0.2893 |
0.3125 |
Ext. |
5/16-28 UN |
3A |
0.0000 |
0.3125 |
0.3060 |
- |
0.2893 |
0.2867 |
0.2699 |
Int. |
|
3B |
|
0.2807 |
0.2740 |
|
0.2926 |
0.2893 |
0.3125 |
Ext. |
5/16-32 UNEF |
2A |
0.0010 |
0.3115 |
0.3055 |
- |
0.2912 |
0.2880 |
0.2743 |
Int. |
|
2B |
|
0.2860 |
0.2790 |
|
0.2964 |
0.2922 |
0.3125 |
Ext. |
5/16-32 UNEF |
3A |
0.0000 |
0.3125 |
0.3065 |
- |
0.2922 |
0.2898 |
0.2753 |
Int. |
|
3B |
|
0.2847 |
0.2790 |
|
0.2953 |
0.2922 |
0.3125 |
Ext. |
5/16-36 UNS |
2A |
0.0009 |
0.3116 |
0.3061 |
- |
0.2936 |
0.2905 |
0.2785 |
Int. |
|
2B |
|
0.2890 |
0.2820 |
|
0.2985 |
0.2945 |
0.3125 |
Ext. |
5/16-40 UNS |
2A |
0.0009 |
0.3116 |
0.3065 |
- |
0.2954 |
0.2925 |
0.2818 |
Int. |
|
2B |
|
0.2910 |
0.2850 |
|
0.3001 |
0.2963 |
0.3125 |
Ext. |
5/16-48 UNS |
2A |
0.0008 |
0.3117 |
0.3072 |
- |
0.2982 |
0.2955 |
0.2869 |
Int. |
|
2B |
|
0.2950 |
0.2900 |
|
0.3026 |
0.2990 |
0.3125 |
Ext. |
3/8-16 UNC |
1A |
0.0013 |
0.3737 |
0.3595 |
- |
0.3331 |
0.3266 |
0.2992 |
Int. |
|
1B |
|
0.3210 |
0.3070 |
|
0.3429 |
0.3344 |
0.3750 |
Ext. |
3/8-16 UNC |
2A |
0.0013 |
0.3737 |
0.3643 |
0.3595 |
0.3331 |
0.3287 |
0.2992 |
Int. |
|
2B |
|
0.3210 |
0.3070 |
|
0.3401 |
0.3344 |
0.3750 |
Ext. |
3/8-16 UNC |
3A |
0.0000 |
0.3750 |
0.3656 |
- |
0.3344 |
0.3311 |
0.3005 |
Int. |
|
3B |
|
0.3182 |
0.3070 |
|
0.3387 |
0.3344 |
0.3750 |
Ext. |
3/8-18 UNS |
2A |
0.0013 |
0.3737 |
0.3650 |
- |
0.3376 |
0.3333 |
0.3076 |
Int. |
|
2B |
|
0.3280 |
0.3150 |
|
0.3445 |
0.3389 |
0.3750 |
Ext. |
3/8-20 UN |
2A |
0.0012 |
0.3738 |
0.3657 |
- |
0.3413 |
0.3372 |
0.3143 |
Int. |
|
2B |
|
0.3320 |
0.3210 |
|
0.3479 |
0.3425 |
0.3750 |
Ext. |
3/8-20 UN |
3A |
0.0000 |
0.3750 |
0.3669 |
- |
0.3425 |
0.3394 |
0.3155 |
Int. |
|
3B |
|
0.3297 |
0.3210 |
|
0.3465 |
0.3425 |
0.3750 |
Ext. |
3/8-24 UNF |
1A |
0.0011 |
0.3739 |
0.3631 |
- |
0.3468 |
0.3411 |
0.3243 |
Int. |
|
1B |
|
0.3400 |
0.3300 |
|
0.3553 |
0.3479 |
0.3750 |
Ext. |
3/8-24 UNF |
2A |
0.0011 |
0.3739 |
0.3667 |
- |
0.3468 |
0.3430 |
0.3243 |
Int. |
|
2B |
|
0.3400 |
0.3300 |
|
0.3528 |
0.3479 |
0.3750 |
Ext. |
3/8-24 UNF |
3A |
0.0000 |
0.3750 |
0.3678 |
- |
0.3479 |
0.3450 |
0.3254 |
Int. |
|
3B |
|
0.3372 |
0.3300 |
|
0.3516 |
0.3479 |
0.3750 |
Ext. |
3/8-27 UNS |
2A |
0.0011 |
0.3739 |
0.3672 |
- |
0.3498 |
0.3462 |
0.3298 |
Int. |
|
2B |
|
0.3440 |
0.3350 |
|
0.3556 |
0.3509 |
0.3750 |
Ext. |
3/8-28 UN |
2A |
0.0011 |
0.3739 |
0.3674 |
- |
0.3507 |
0.3471 |
0.3313 |
Int. |
|
2B |
|
0.3450 |
0.3360 |
|
0.3564 |
0.3518 |
0.3750 |
Ext. |
3/8-28 UN |
3A |
0.0000 |
0.3750 |
0.3685 |
- |
0.3518 |
0.3491 |
0.3324 |
Int. |
|
3B |
|
0.3426 |
0.3360 |
|
0.3553 |
0.3518 |
0.3750 |
Ext. |
3/8-32 UNEF |
2A |
0.0010 |
0.3740 |
0.3680 |
- |
0.3537 |
0.3503 |
0.3368 |
Int. |
|
2B |
|
0.3490 |
0.3410 |
|
0.3591 |
0.3547 |
0.3750 |
Ext. |
3/8-32 UNEF |
3A |
0.0000 |
0.3750 |
0.3690 |
- |
0.3547 |
0.3522 |
0.3378 |
Int. |
|
3B |
|
0.3469 |
0.3410 |
|
0.3580 |
0.3547 |
0.3750 |
Ext. |
3/8-36 UNS |
2A |
0.0010 |
0.3740 |
0.3685 |
- |
0.3560 |
0.3528 |
0.3409 |
Int. |
|
2B |
|
0.3520 |
0.3450 |
|
0.3612 |
0.3570 |
0.3750 |
Ext. |
3/8-40 UNS |
2A |
0.0009 |
0.3741 |
0.3690 |
- |
0.3579 |
0.3548 |
0.3443 |
Int. |
|
2B |
|
0.3540 |
0.3480 |
|
0.3628 |
0.3588 |
0.3750 |
Ext. |
0.390—27 UNS |
2A |
0.0011 |
0.3889 |
0.3822 |
- |
0.3648 |
0.3612 |
0.3448 |
Int. |
|
2B |
|
0.3590 |
0.3500 |
|
0.3706 |
0.3659 |
0.3900 |
Ext. |
7/16-14 UNC |
1A |
0.0014 |
0.4361 |
0.4206 |
- |
0.3897 |
0.3826 |
0.3511 |
Int. |
|
1B |
|
0.3760 |
0.3600 |
|
0.4003 |
0.3911 |
0.4375 |
Ext. |
7/16-14 UNC |
2A |
0.0014 |
0.4361 |
0.4258 |
0.4206 |
0.3897 |
0.3850 |
0.3511 |
Int. |
|
2B |
|
0.3760 |
0.3600 |
|
0.3972 |
0.3911 |
0.4375 |
Ext. |
7/16-14 UNC |
3A |
0.0000 |
0.4375 |
0.4272 |
- |
0.3911 |
0.3876 |
0.3525 |
Int. |
|
3B |
|
0.3717 |
0.3600 |
|
0.3957 |
0.3911 |
0.4375 |
Ext. |
7/16-16 UN |
2A |
0.0014 |
0.4361 |
0.4267 |
- |
0.3955 |
0.3909 |
0.3616 |
Int. |
|
2B |
|
0.3840 |
0.3700 |
|
0.4028 |
0.3969 |
0.4375 |
Ext. |
7/16-16 UN |
3A |
0.0000 |
0.4375 |
0.4281 |
- |
0.3969 |
0.3935 |
0.3630 |
Int. |
|
3B |
|
0.3800 |
0.3700 |
|
0.4014 |
0.3969 |
0.4375 |
Ext. |
7/16-18 UNS |
2A |
0.0013 |
0.4362 |
0.4275 |
- |
0.4001 |
0.3958 |
0.3701 |
Int. |
|
2B |
|
0.3900 |
0.3770 |
|
0.4070 |
0.4014 |
0.4375 |
Ext. |
7/16-20 UNF |
1A |
0.0013 |
0.4362 |
0.4240 |
- |
0.4037 |
0.3975 |
0.3767 |
Int. |
|
1B |
|
0.3950 |
0.3830 |
|
0.4131 |
0.4050 |
0.4375 |
Ext. |
7/16-20 UNF |
2A |
0.0013 |
0.4362 |
0.4281 |
- |
0.4037 |
0.3995 |
0.3767 |
Int. |
|
2B |
|
0.3950 |
0.3830 |
|
0.4104 |
0.4050 |
0.4375 |
Ext. |
7/16-20 UNF |
3A |
0.0000 |
0.4375 |
0.4294 |
- |
0.4050 |
0.4019 |
0.3780 |
Int. |
|
3B |
|
0.3916 |
0.3830 |
|
0.4091 |
0.4050 |
0.4375 |
Ext. |
7/16-24 UNS |
2A |
0.0011 |
0.4364 |
0.4292 |
- |
0.4093 |
0.4055 |
0.3868 |
Int. |
|
2B |
|
0.4020 |
0.3920 |
|
0.4153 |
0.4104 |
0.4375 |
Ext. |
7/16-27 UNS |
2A |
0.0011 |
0.4364 |
0.4297 |
- |
0.4123 |
0.4087 |
0.3923 |
Int. |
|
2B |
|
0.4060 |
0.3970 |
|
0.4181 |
0.4134 |
0.4375 |
Ext. |
7/16-28 UNEF |
2A |
0.0011 |
0.4364 |
0.4299 |
- |
0.4132 |
0.4096 |
0.3838 |
Int. |
|
2B |
|
0.4070 |
0.3990 |
|
0.4189 |
0.4143 |
0.4375 |
Ext. |
7/16-28 UNEF |
3A |
0.0000 |
0.4375 |
0.4310 |
- |
0.4143 |
0.4116 |
0.3949 |
Int. |
|
3B |
|
0.4051 |
0.3990 |
|
0.4178 |
0.4143 |
0.4375 |
Ext. |
7/16-32 UN |
2A |
0.0010 |
0.4365 |
0.4305 |
- |
0.4162 |
0.4128 |
0.3993 |
Int. |
|
2B |
|
0.4110 |
0.4040 |
|
0.4216 |
0.4172 |
0.4375 |
Ext. |
7/16-32 UN |
3A |
0.0000 |
0.4375 |
0.4315 |
- |
0.4172 |
0.4147 |
0.4003 |
Int. |
|
3B |
|
0.4094 |
0.4040 |
|
0.4205 |
0.4172 |
0.4375 |
Ext. |
1/2-12 UNS |
2A |
0.0016 |
0.4984 |
0.4870 |
- |
0.4443 |
0.4389 |
0.3992 |
Int. |
|
2B |
|
0.4280 |
0.4100 |
|
0.4529 |
0.4459 |
0.5000 |
Ext. |
1/2-12 UNS |
3A |
0.0000 |
0.5000 |
0.4886 |
- |
0.4459 |
0.4419 |
0.4008 |
Int. |
|
3B |
|
0.4223 |
0.4100 |
|
0.4511 |
0.4459 |
0.5000 |
Ext. |
1/2-13 UNC |
1A |
0.0015 |
0.4985 |
0.4822 |
- |
0.4485 |
0.4411 |
0.4069 |
Int. |
|
1B |
|
0.4340 |
0.4170 |
|
0.4597 |
0.4500 |
0.5000 |
Ext. |
1/2-13 UNC |
2A |
0.0015 |
0.4985 |
0.4876 |
0.4822 |
0.4485 |
0.4435 |
0.4069 |
Int. |
|
2B |
|
0.4340 |
0.4170 |
|
0.4565 |
0.4500 |
0.5000 |
Ext. |
1/2-13 UNC |
3A |
0.0000 |
0.5000 |
0.4891 |
- |
0.4500 |
0.4463 |
0.4084 |
Int. |
|
3B |
|
0.4284 |
0.4170 |
|
0.4548 |
0.4500 |
0.5000 |
Ext. |
1/2-14 UNS |
2A |
0.0015 |
0.4985 |
0.4882 |
- |
0.4521 |
0.4471 |
0.4135 |
Int. |
|
2B |
|
0.4380 |
0.4230 |
|
0.4601 |
0.4536 |
0.5000 |
Ext. |
1/2-16 UN |
2A |
0.0000 |
0.4986 |
0.4892 |
- |
0.4580 |
0.4533 |
0.4241 |
Int. |
|
2B |
|
0.4460 |
0.4320 |
|
0.4655 |
0.4594 |
0.5000 |
Ext. |
1/2-16 UN |
3A |
0.0000 |
0.5000 |
0.4906 |
- |
0.4594 |
0.4559 |
0.4255 |
Int. |
|
3B |
|
0.4419 |
0.4320 |
|
0.4640 |
0.4594 |
0.5000 |
Ext. |
1/2-18 UNS |
2A |
0.0013 |
0.4987 |
0.4900 |
- |
0.4626 |
0.4582 |
0.4326 |
Int. |
|
2B |
|
0.4530 |
0.4400 |
|
0.4697 |
0.4639 |
0.5000 |
Ext. |
1/2-20 UNF |
1A |
0.0013 |
0.4987 |
0.4865 |
- |
0.4662 |
0.4598 |
0.4392 |
Int. |
|
1B |
|
0.4570 |
0.4460 |
|
0.4759 |
0.4675 |
0.5000 |
Ext. |
1/2-20 UNF |
2A |
0.0013 |
0.4987 |
0.4906 |
- |
0.4662 |
0.4619 |
0.4392 |
Int. |
|
2B |
|
0.4570 |
0.4460 |
|
0.4731 |
0.4675 |
0.5000 |
Ext. |
1/2-20 UNF |
3A |
0.0000 |
0.5000 |
0.4919 |
- |
0.4675 |
0.4643 |
0.4405 |
Int. |
|
3B |
|
0.4537 |
0.4460 |
|
0.4717 |
0.4675 |
0.5000 |
Ext. |
1/2-24 UNS |
2A |
0.0012 |
0.4988 |
0.4916 |
- |
0.4717 |
0.4678 |
0.4492 |
Int. |
|
2B |
|
0.4650 |
0.4550 |
|
0.4780 |
0.4729 |
0.5000 |
Ext. |
1/2-27 UNS |
2A |
0.0011 |
0.4989 |
0.4922 |
- |
0.4748 |
0.4711 |
0.4548 |
Int. |
|
2B |
|
0.4690 |
0.4600 |
|
0.4807 |
0.4759 |
0.5000 |
Ext. |
1/2-28 UNEF |
2A |
0.0011 |
0.4989 |
0.4924 |
- |
0.4757 |
0.4720 |
0.4563 |
Int. |
|
2B |
|
0.4700 |
0.4610 |
|
0.4816 |
0.4768 |
0.5000 |
Ext. |
1/2-28 UNEF |
3A |
0.0000 |
0.5000 |
0.4935 |
- |
0.4768 |
0.4740 |
0.4574 |
Int. |
|
3B |
|
0.4676 |
0.4610 |
|
0.4804 |
0.4768 |
0.5000 |
Ext. |
1/2-32 UN |
2A |
0.0010 |
0.4990 |
0.4930 |
- |
0.4787 |
0.4752 |
0.4618 |
Int. |
|
2B |
|
0.4740 |
0.4660 |
|
0.4842 |
0.4797 |
0.5000 |
Ext. |
1/2-32 UN |
3A |
0.0000 |
0.5000 |
0.4940 |
- |
0.4797 |
0.4771 |
0.4628 |
Int. |
|
3B |
|
0.4719 |
0.4660 |
|
0.4831 |
0.4797 |
0.5000 |
Ext. |
9/16-12 UNC |
1A |
0.0016 |
0.5609 |
0.5437 |
- |
0.5068 |
0.4990 |
0.4617 |
Int. |
|
1B |
|
0.4900 |
0.4720 |
|
0.5186 |
0.5084 |
0.5625 |
Ext. |
9/16-12 UNC |
2A |
0.0016 |
0.5609 |
0.5495 |
0.5437 |
0.5068 |
0.5016 |
0.4617 |
Int. |
|
2B |
|
0.4900 |
0.4720 |
|
0.5152 |
0.5084 |
0.5625 |
Ext. |
9/16-12 UNC |
3A |
0.0000 |
0.5625 |
0.5511 |
- |
0.5084 |
0.5045 |
0.4633 |
Int. |
|
3B |
|
0.4843 |
0.4720 |
|
0.5135 |
0.5084 |
0.5625 |
Ext. |
9/16-14 UNS |
2A |
0.0015 |
0.5610 |
0.5507 |
- |
0.5146 |
0.5096 |
0.4760 |
Int. |
|
2B |
|
0.5010 |
0.4850 |
|
0.5226 |
0.5161 |
0.5625 |
Ext. |
9/16-16 UN |
2A |
0.0014 |
0.5611 |
0.5517 |
- |
0.5205 |
0.5158 |
0.4866 |
Int. |
|
2B |
|
0.5090 |
0.4950 |
|
0.5280 |
0.5219 |
0.5625 |
Ext. |
9/16-16 UN |
3A |
0.0000 |
0.5625 |
0.5531 |
- |
0.5219 |
0.5184 |
0.4880 |
Int. |
|
3B |
|
0.5040 |
0.4950 |
|
0.5265 |
0.5219 |
0.5625 |
Ext. |
9/16-18 UNF |
1A |
0.0014 |
0.5611 |
0.5480 |
- |
0.5250 |
0.5182 |
0.4950 |
Int. |
|
1B |
|
0.5150 |
0.5020 |
|
0.5353 |
0.5264 |
0.5625 |
Ext. |
9/16-18 UNF |
2A |
0.0014 |
0.5611 |
0.5524 |
- |
0.5250 |
0.5205 |
0.4950 |
Int. |
|
2B |
|
0.5150 |
0.5020 |
|
0.5323 |
0.5264 |
0.5625 |
Ext. |
9/16-18 UNF |
3A |
0.0000 |
0.5625 |
0.5538 |
- |
0.5264 |
0.5230 |
0.4964 |
Int. |
|
3B |
|
0.5106 |
0.5020 |
|
0.5308 |
0.5264 |
0.5625 |
Ext. |
9/16-20 UN |
2A |
0.0013 |
0.5612 |
0.5531 |
- |
0.5287 |
0.5245 |
0.5017 |
Int. |
|
2B |
|
0.5200 |
0.5080 |
|
0.5355 |
0.5300 |
0.5625 |
Ext. |
9/16-20 UN |
3A |
0.0000 |
0.5625 |
0.5544 |
- |
0.5300 |
0.5268 |
0.5030 |
Int. |
|
3B |
|
0.5162 |
0.5080 |
|
0.5341 |
0.5300 |
0.5625 |
Ext. |
9/16-24 UNEF |
2A |
0.0012 |
0.5613 |
0.5541 |
- |
0.5342 |
0.5303 |
0.5117 |
Int. |
|
2B |
|
0.5270 |
0.5170 |
|
0.5405 |
0.5354 |
0.5625 |
Ext. |
9/16-24 UNEF |
3A |
0.0000 |
0.5625 |
0.5553 |
- |
0.5354 |
0.5325 |
0.5129 |
Int. |
|
3B |
|
0.5244 |
0.5170 |
|
0.5392 |
0.5354 |
0.5625 |
Ext. |
9/16-27 UNS |
2A |
0.0011 |
0.5614 |
0.5547 |
- |
0.5373 |
0.5336 |
0.5173 |
Int. |
|
2B |
|
0.5310 |
0.5220 |
|
0.5432 |
0.5384 |
0.5625 |
Ext. |
9/16-28 UN |
2A |
0.0011 |
0.5614 |
0.5549 |
- |
0.5382 |
0.5345 |
0.5188 |
Int. |
|
2B |
|
0.5320 |
0.5240 |
|
0.5441 |
0.5393 |
0.5625 |
Ext. |
9/16-28 UN |
3A |
0.0000 |
0.5625 |
0.5560 |
- |
0.5393 |
0.5365 |
0.5199 |
Int. |
|
3B |
|
0.5301 |
0.5240 |
|
0.5429 |
0.5393 |
0.5625 |
Ext. |
9/16-32 UN |
2A |
0.0010 |
0.5615 |
0.5555 |
- |
0.5412 |
0.5377 |
0.5243 |
Int. |
|
2B |
|
0.5360 |
0.5290 |
|
0.5467 |
0.5422 |
0.5625 |
Ext. |
9/16-32 UN |
3A |
0.0000 |
0.5625 |
0.5565 |
- |
0.5422 |
0.5396 |
0.5253 |
Int. |
|
3B |
|
0.5344 |
0.5290 |
|
0.5456 |
0.5422 |
0.5625 |
a For Class 2A threads with coating (plating) the max. is increased by the allowance, to the basic size. This is the same value as Class 3A. |
b For uncoated hot-rolled, but not standard fasteners with cold rolled threads |
c UN series external thread, Max.Diameter |
= |
Basic - Allowance, for Class 1A and 2A |
|
= | Basic for Class 3A |
|