Hex Nut Size Chart & Dimensions
This chart gives the standard width across flats (which is also the wrench size) and thickness for finished hex nuts, in inch and metric. Use it to pick a wrench or socket, check clearances, or confirm you have the right nut. Heavy hex nuts are larger across the flats and taller than the finished hex sizes shown here.
Inch Finished Hex Nut Chart
| Thread Size | Width Across Flats (Wrench Size) | Thickness |
|---|---|---|
| #8-32 | 11/32" | 7/64" |
| #10-24 / #10-32 | 3/8" | 1/8" |
| 1/4-20 | 7/16" | 7/32" |
| 5/16-18 | 1/2" | 17/64" |
| 3/8-16 | 9/16" | 21/64" |
| 7/16-14 | 11/16" | 3/8" |
| 1/2-13 | 3/4" | 7/16" |
| 9/16-12 | 7/8" | 31/64" |
| 5/8-11 | 15/16" | 35/64" |
| 3/4-10 | 1-1/8" | 41/64" |
| 7/8-9 | 1-5/16" | 3/4" |
| 1-8 | 1-1/2" | 55/64" |
Metric Hex Nut Chart
| Thread Size | Width Across Flats (Wrench Size) | Thickness |
|---|---|---|
| M5 | 8 mm | 4.7 mm |
| M6 | 10 mm | 5.2 mm |
| M8 | 13 mm | 6.8 mm |
| M10 | 17 mm | 8.4 mm |
| M12 | 19 mm | 10.8 mm |
| M14 | 22 mm | 12.8 mm |
| M16 | 24 mm | 14.8 mm |
| M20 | 30 mm | 18.0 mm |
| M24 | 36 mm | 21.5 mm |
Reference values for standard finished hex nuts (inch per ASME B18.2.2; metric per ISO 4032 / DIN 934). Some metric sizes have an alternate width across flats (for example M10 = 16 mm and M12 = 18 mm in the older DIN pattern); confirm against your hardware. Heavy hex, jam, and structural nuts differ — ask us for exact specs.
Frequently Asked Questions
What size wrench fits a hex nut?
The wrench size equals the nut's width across flats. For example a 1/2-13 hex nut takes a 3/4 inch wrench, and an M12 nut takes a 19 mm wrench. Use the charts above to match wrench or socket to nut.
What wrench size is a 1/2 inch nut?
A standard 1/2-13 finished hex nut has a 3/4 inch width across flats, so it takes a 3/4 inch wrench or socket. A heavy hex 1/2 inch nut is larger; confirm before selecting a tool.
How thick is a hex nut?
A finished hex nut's thickness is roughly 7/8 of its thread diameter (for example a 1/2 inch nut is about 7/16 inch thick). Jam nuts are about half that; heavy hex nuts are taller. See the charts for exact values.
Are heavy hex nuts a different wrench size?
Yes. Heavy hex nuts are wider across the flats than finished hex nuts of the same thread, so they take a larger wrench. Always size the wrench to the actual nut you have.
Need Hex Nuts in Any Size?
Inch and metric, every grade and material, by the piece or in bulk.