Size picker · Nyloc nut · IFI-100/107
UNC and UNF nyloc nut sizes.
The imperial nylon insert lock nut — and the page to check before you reach for a spanner, because an inch nyloc is a light hex and does not take the spanner the full nut beside it does.
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Drawn to proportion from the standard dimensions. Illustration, not a photograph of the item.
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| Sym | Dimension | Value |
|---|
Job stopped? Ring 01327 877577 and we'll check the stock while you're on.
Read the full nut size chart
| Size | Thread | s — across flats | e — across corners | m — height |
|---|---|---|---|---|
| 20 UNC · 28 UNF | 0.438" | 0.507" | 0.313" | |
| 18 UNC · 24 UNF | 1/2" | 0.580" | 0.344" | |
| 16 UNC · 24 UNF | 0.562" | 0.650" | 0.453" | |
| 14 UNC · 20 UNF | 5/8" | 0.724" | 0.453" | |
| 13 UNC · 20 UNF | 3/4" | 0.868" | 0.594" | |
| 12 UNC · 18 UNF | 7/8" | 1.013" | 0.640" | |
| 11 UNC · 18 UNF | 0.938" | 1.085" | 3/4" | |
| 10 UNC · 16 UNF | 1.063" | 1.229" | 7/8" | |
| 9 UNC · 14 UNF | 1 1/4" | 1.446" | 0.984" | |
| 8 UNC · 12 UNF | 1.440" | 1.663" | 1.047" |
Figures are the standards' nominal dimensions, each confirmed against two independent published tables — anything we could only source once reads "ask us" rather than printing a number we can't stand behind. Odd diameters like M7 and M9, left-hand threads and the finer pitches are all made, and availability varies by finish and class — ask us for anything you can't see.Figures are the standards' nominal dimensions, each confirmed against two independent published tables. Where only one table prints a figure, where two disagree, or where nobody publishes one at all, the row reads "ask us" rather than a number we can't stand behind. Imperial washers (BS 3410), the other BS 4320 forms, spring and shakeproof patterns and the hardness grades are all real too, and availability varies by finish — ask us for anything you can't see.
The light-hex trap
An imperial nyloc follows IFI-100/107's light hex pattern, not the full nut's B18.2.2 widths. Four sizes bite: 7/16 takes a 5/8 spanner where the full nut takes 11/16 · 3/4 takes 1 1/16 not 1 1/8 · 7/8 takes 1 1/4 not 1 5/16 · 1 inch takes 1 7/16 not 1 1/2. Both of the published tables this chart is built from agree on all four. The metric instinct — nyloc shares the full nut's spanner — is exactly wrong here.
The nylon has limits
The insert grips from about −50°C to +120°C, and its grip weakens every time the nut comes off. No standard publishes a number of reuses you can rely on, so on anything that matters, fit a new one. Hotter than the nylon will take? Ask us about all-metal imperial locking — that is what a K-nut is for.
Finishes
Imperial nylocs are listed in bright zinc, 18-8 and 316 stainless. Nobody lists a self-colour one, so this page does not offer it.
Working in metric instead?
See the metric nyloc chart for DIN 985, or the UNC and UNF full nut chart for the plain nut.
Not sure which you need?
Bring the old one in, or send us a photo. We are on Baird Close in Daventry, and UNF nylocs are a stock line here — motorsport keeps them moving.
More size charts
Every size, drawn to scale.
Hex setscrews
DIN 933 · full thread
Hex bolts
DIN 931 · part thread
Socket cap screws
DIN 912
Low head cap screws
DIN 7984
Button head screws
ISO 7380-1
Flanged button heads
ISO 7380-2
Countersunk socket screws
DIN 7991
Grub screws
DIN 913–916 · five points
Nuts
DIN 934 · nyloc · thin · Stover · flange
Washers
ISO 7089 · BS 4320 · penny
Not sure what the markings on the head mean? Bolt grades explained covers 8.8, 10.9, 12.9, stainless A2 and A4, and the imperial SAE grades.
All of it comes off the shelf at Baird Close — see the full fasteners & fixings range, or every size guide.