Size picker · Full nut · ASME B18.2.2
UNC and UNF full nut sizes.
The imperial hex nut. Pick a diameter for the spanner size, across-corners and thickness, drawn to proportion — and pick UNC or UNF, because a nut is its thread and the two will not interchange.
1 Pick a diameter
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Drawn to proportion from the standard dimensions. Illustration, not a photograph of the item.
Selected
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| Sym | Dimension | Value |
|---|
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Read the full nut size chart
| Size | Thread | s — across flats | e — across corners | m — height |
|---|---|---|---|---|
| 20 UNC · 28 UNF | 0.438" | 0.505" | 0.226" | |
| 18 UNC · 24 UNF | 1/2" | 0.577" | 0.273" | |
| 16 UNC · 24 UNF | 0.562" | 0.650" | 0.337" | |
| 14 UNC · 20 UNF | 0.688" | 0.794" | 0.385" | |
| 13 UNC · 20 UNF | 3/4" | 0.866" | 0.448" | |
| 12 UNC · 18 UNF | 7/8" | 1.010" | 0.496" | |
| 11 UNC · 18 UNF | 0.938" | 1.083" | 0.559" | |
| 10 UNC · 16 UNF | 1 1/8" | 1.299" | 0.665" | |
| 9 UNC · 14 UNF | 1.312" | 1.516" | 0.776" | |
| 8 UNC · 12 UNF | 1 1/2" | 1.732" | 0.887" | |
| 7 UNC · 12 UNF | 1.688" | 1.949" | 0.999" |
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 spanner sizes are not the metric habit
Imperial spanners are marked across the flats, and the figures follow ASME B18.2.2: a 1/4 inch nut takes a 7/16 spanner, a 1/2 inch takes 3/4, and a 7/16 inch takes 11/16 — worth saying because the imperial nyloc at that same size takes a 5/8, which catches people who assume the two share a spanner.
No class 8 here
An inch nut is not classed like a metric one. The everyday steel nut is SAE Grade 2 (proof load 90,000 psi coarse, 80,000 fine), and stainless comes as 18-8 — the inch trade's word for A2 — or 316 for marine and chemical work. If a drawing calls for Grade 5 or Grade 8 nuts we can get them; say so when you order.
Where these figures come from
Every dimension is ASME B18.2.2, read from two independent published tables that agree to the thousandth. The sizes offered are the ones our suppliers actually list — gauge sizes below 1/4 inch exist but barely trade, so they are to order rather than on the chart.
Working in metric instead?
See the metric full nut chart for DIN 934, or the UNC and UNF hex bolt chart for what these go on.
Not sure which you need?
Bring the old one in, or send us a photo. We are on Baird Close in Daventry with imperial nuts on the shelf in the common sizes.
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.