Wrench size, thickness and hex height for nylon-insert hex lock nuts (NE, standard height), 1/4″ to 1-1/2″. ASME B18.16.6.
A nylon-insert lock nut (“nylock”) is a hex nut with a nylon ring in its top. When the bolt reaches the ring, the threads cut into the nylon for a tight fit that holds the nut against vibration. The nut is taller than a plain hex nut to make room for the ring — and at 7/16″ and from 3/4″ up it uses a light hex, so it takes a smaller wrench than a hex nut of the same size.
Letters match the table columns: F across flats (the wrench), H overall thickness, Q hex (wrenching) height.
| Size | Wrench F | F max / min | Thickness H max / min | Hex height Q min |
|---|---|---|---|---|
| 1/4″ | 7/16″ | .439 / .430 | .328 / .298 | .225 |
| 5/16″ | 1/2″ | .502 / — | .359 / .329 | .250 |
| 3/8″ | 9/16″ | .564 / — | .468 / .438 | .335 |
| 7/16″ | 5/8″ | .627 / .616 | .468 / .438 | .324 |
| 1/2″ | 3/4″ | .752 / — | .609 / .579 | .464 |
| 9/16″ | 7/8″ | .877 / — | .656 / .626 | .469 |
| 5/8″ | 15/16″ | .940 / — | .765 / .735 | .593 |
| 3/4″ | 1-1/16″ | 1.064 / 1.052 | .890 / .860 | .742 |
| 7/8″ | 1-1/4″ | 1.252 / 1.239 | .999 / .969 | .790 |
| 1″ | 1-7/16″ | 1.440 / 1.427 | 1.078 / 1.016 | .825 |
| 1-1/8″ | 1-5/8″ | 1.627 / 1.614 | 1.203 / 1.141 | .930 |
| 1-1/4″ | 1-13/16″ | 1.815 / 1.801 | 1.422 / 1.360 | 1.125 |
| 1-1/2″ | 2-3/16″ | 2.197 / 2.159 | 1.640 / 1.578 | 1.313 |
Smaller wrench than a standard hex nut: 7/16″ takes 5/8″ (a hex nut: 11/16″), 3/4″ takes 1-1/16″ (a hex nut: 1-1/8″), 7/8″ takes 1-1/4″ (a hex nut: 1-5/16″), 1″ takes 1-7/16″ (a hex nut: 1-1/2″), 1-1/8″ takes 1-5/8″ (a hex nut: 1-11/16″), 1-1/4″ takes 1-13/16″ (a hex nut: 1-7/8″), 1-1/2″ takes 2-3/16″ (a hex nut: 2-1/4″). Same nut for coarse and fine thread. A dash: our two sources differ — give us a call at 405-670-1234.
| Size | Wrench F | F max / min | Thickness H max / min | Hex height Q (ref) |
|---|---|---|---|---|
| #2 | 1/4″ | .251 / .243 | .124 / .094 | .075 |
| #4 | 1/4″ | .251 / .243 | .124 / .094 | .075 |
| #6 | 5/16″ | .313 / .305 | .140 / .110 | .090 |
| #8 | 11/32″ | .345 / .336 | .187 / .157 | .110 |
| #10 | 3/8″ | .376 / .367 | .187 / .157 | .110 |
| #12 | 7/16″ | .439 / .430 | .218 / .188 | .125 |
| 1/4″ | 7/16″ | .439 / .430 | .218 / .188 | .125 |
| 5/16″ | 1/2″ | .502 / .492 | .265 / .235 | .158 |
| 3/8″ | 9/16″ | .564 / .553 | .281 / .251 | .150 |
| 7/16″ | 5/8″ | .627 / .615 | .328 / .298 | .225 |
| 1/2″ | 3/4″ | .752 / .741 | .328 / .298 | .190 |
| 9/16″ | 7/8″ | .877 / .865 | .374 / .344 | .225 |
| 5/8″ | 15/16″ | .940 / .928 | .406 / .376 | .265 |
| 3/4″ | — | — / 1.052 | .421 / .391 | .288 |
| 1″ | 1-7/16″ | 1.440 / 1.427 | .578 / .516 | .405 |
A thinner nylon-insert nut for tight spots and jam use. A dash: our two sources differ — give us a call.
| Size | Wrench F | F max / min | Thickness H max / min | Hex height Q |
|---|---|---|---|---|
| 1/4″ | 1/2″ | .503 / .489 | .390 / .360 | — |
| 5/16″ | 9/16″ | .566 / .551 | .453 / .423 | — |
| 3/8″ | 11/16″ | .691 / .675 | .562 / .532 | — |
| 1/2″ | 7/8″ | .879 / .861 | .718 / .688 | — |
| 5/8″ | 1-1/16″ | 1.067 / 1.045 | .874 / .844 | — |
| 3/4″ | — | — / 1.231 | 1.015 / .985 | — |
| 7/8″ | 1-7/16″ | 1.444 / 1.417 | 1.140 / 1.110 | — |
| 1″ | 1-5/8″ | 1.632 / 1.602 | 1.312 / 1.250 | — |
| 1-1/4″ | 2″ | 2.008 / 1.973 | 1.672 / 1.610 | — |
| 1-3/4″ | 2-3/4″ | 2.762 / 2.715 | 2.376 / 2.250 | — |
| 2″ | 3-1/8″ | 3.137 / 3.086 | 2.469 / 2.343 | — |
Heavy hex: a bigger wrench and a thicker nut than the NE. A dash: our two sources differ — give us a call.
| Size | Wrench F | F max / min | Thickness H max / min | Hex height Q |
|---|---|---|---|---|
| #4 | 1/4″ | .251 / — | .153 / — | — |
| #6 | 5/16″ | .313 / — | .188 / — | — |
| #8 | 11/32″ | .345 / — | .239 / — | — |
| #10 | 3/8″ | .376 / — | .249 / — | — |
| #12 | 7/16″ | .439 / — | .328 / — | — |
Maximum sizes (one of our sources gives maximums only).
Good to know
The nylon ring has a temperature limit, so for hot work use an all-metal lock nut — ask us for the rating. Other lock nuts and nut styles are on Nut Types & When to Use Them; standard hex nuts on the hex nut chart.
Quick answers
- What size wrench fits a 3/8" nylock nut?
- A 3/8″ nylon-insert lock nut takes a 9/16″ wrench.
- What wrench size goes with each nylon-insert lock nut size?
- 1/4″ – 7/16″, 5/16″ – 1/2″, 3/8″ – 9/16″, 7/16″ – 5/8″, 1/2″ – 3/4″, 9/16″ – 7/8″, 5/8″ – 15/16″, 3/4″ – 1-1/16″, 7/8″ – 1-1/4″, 1″ – 1-7/16″, 1-1/8″ – 1-5/8″, 1-1/4″ – 1-13/16″, 1-1/2″ – 2-3/16″.
- Why does my 3/4" nylock nut take a smaller wrench than a 3/4" hex nut?
- Nylon-insert lock nuts at 7/16″ and from 3/4″ up use a light hex: a 3/4″ one takes 1-1/16″, a 3/4″ hex nut takes 1-1/8″.
- How thick is a 1/2" nylon-insert lock nut?
- .579–.609″ (ASME B18.16.6, standard height).