Nut Diameter Chart
Which wrench fits a 3/8-inch nut? What is the thread pitch of an M8 bolt? This printable pack answers both with inch and metric hex nut charts — bolt diameter, wrench size across flats, nut thickness and threads — plus an actual-size bolt gauge you can hold a bolt against, and an Excel lookup sheet for the workshop.
Nut & Bolt Size Chart Pack
Printable inch and metric hex nut charts (wrench size, thickness, threads), an actual-size bolt diameter gauge, a bolt grade marking chart and an Excel fastener lookup.
- Inch nut chart (PDF/XLSX)
- Metric nut chart (PDF/XLSX)
- Bolt gauge (PDF)
- Grade chart (PDF)
- Fastener lookup (XLSX)
Formats: PDF, XLSX. Instant download after payment (link valid 72 hours, up to 5 downloads). AI-assisted: the templates were drafted with AI help and reviewed and laid out by Kedop.
$5.00 USD, one-time
Secure card checkout by Stripe. Full refund within 7 days — see the refund policy and license.
Inch hex nut chart (finished hex nuts)
| Bolt diameter (in) | Wrench size (in) | Nut thickness (in) | UNC threads/in | UNF threads/in |
|---|---|---|---|---|
| 1/4 | 7/16 | 7/32 | 20 | 28 |
| 5/16 | 1/2 | 17/64 | 18 | 24 |
| 3/8 | 9/16 | 21/64 | 16 | 24 |
| 7/16 | 11/16 | 3/8 | 14 | 20 |
| 1/2 | 3/4 | 7/16 | 13 | 20 |
| 9/16 | 7/8 | 31/64 | 12 | 18 |
| 5/8 | 15/16 | 35/64 | 11 | 18 |
| 3/4 | 1-1/8 | 41/64 | 10 | 16 |
| 7/8 | 1-5/16 | 3/4 | 9 | 14 |
| 1 | 1-1/2 | 55/64 | 8 | 12 |
Dimensions for standard finished hex nuts (ASME B18.2.2). Heavy hex and jam nuts have different widths or thicknesses.
Metric hex nut chart
| Thread | Wrench size (mm) | Nut thickness (mm) | Coarse pitch (mm) |
|---|---|---|---|
| M3 | 5.5 | 2.4 | 0.5 |
| M4 | 7 | 3.2 | 0.7 |
| M5 | 8 | 4.7 | 0.8 |
| M6 | 10 | 5.2 | 1 |
| M8 | 13 | 6.8 | 1.25 |
| M10 | 16 | 8.4 | 1.5 |
| M12 | 18 | 10.8 | 1.75 |
| M14 | 21 | 12.8 | 2 |
| M16 | 24 | 14.8 | 2 |
| M20 | 30 | 18.0 | 2.5 |
| M24 | 36 | 21.5 | 3 |
| M30 | 46 | 25.6 | 3.5 |
Wrench sizes follow ISO 4032. Some older DIN 934 nuts use different sizes: M10 = 17 mm, M12 = 19 mm, M14 = 22 mm.
Nut size vs wrench size
A nut is named by the diameter of the bolt it fits, not by its own outside size. A 1/2-inch nut fits a 1/2-inch bolt and takes a 3/4-inch wrench; an M8 nut fits an 8 mm bolt and takes a 13 mm wrench. The wrench size is the distance across the flats of the hexagon. When a nut is labelled only with a wrench size, use the chart in reverse to find the bolt diameter.
Coarse vs fine threads
| Thread | Pros | Typical uses |
|---|---|---|
| UNC / metric coarse | Faster to assemble, less likely to cross-thread, better in soft materials | General construction, machinery, most hardware |
| UNF / metric fine | Greater tensile strength, finer adjustment, less likely to loosen under vibration | Automotive, aerospace, precision equipment |
A nut must match both the diameter and the thread pitch of its bolt. Use a thread pitch gauge or compare with a known bolt if you are not sure.
How to measure a bolt
- Measure the outside diameter of the threads with calipers (or use the actual-size gauge sheet).
- Count threads per inch, or measure pitch in mm between adjacent threads.
- Measure length from under the head to the tip (for flat-head screws, the overall length).
- Identify the grade marking on the head for strength.
Bolt grade markings
| Marking | Grade | Typical use |
|---|---|---|
| No marks (inch) | Grade 2 | Light-duty |
| 3 radial lines | SAE Grade 5 | Automotive, general machinery |
| 6 radial lines | SAE Grade 8 | High-strength applications |
| 8.8 (metric) | Property class 8.8 | General high-strength |
| 10.9 (metric) | Property class 10.9 | High-strength automotive |
| 12.9 (metric) | Property class 12.9 | Very high strength |
Use nuts of matching or higher grade than the bolt.
What is in the pack
- Inch hex nut chart with wrench size, thickness and UNC/UNF threads.
- Metric hex nut chart with wrench size, thickness and coarse pitch.
- Actual-size bolt diameter gauge (print at 100%).
- Bolt grade marking chart.
- Excel fastener lookup with wrench sizes and tap drill notes.
Formats
Print-ready PDF charts and gauge (US Letter; A4 at 100%), plus an Excel lookup workbook.
Frequently asked questions
What size wrench for a 3/8 bolt?
9/16 inch for a standard 3/8-inch hex nut.
What size wrench for an M8 nut?
13 mm.
What is the thread pitch of M10?
1.5 mm coarse (1.25 mm fine).
Is a 1/2 inch nut 1/2 inch wide?
No — it fits a 1/2-inch bolt and is 3/4 inch across the flats.
Was AI used to create the charts?
The charts were generated by script from standard dimensions and text drafted with AI assistance, then reviewed by Kedop.