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Filter the table by size, symbol, process, value, or application without scanning the whole chart.
Mechanical design reference
Imperial Bolt Dimensions
Search imperial bolt thread sizes, major and minor diameters, TPI, tapping drill sizes, and clearance hole sizes for inch-based fastener design.
Design reference
Search imperial bolt dimensions
Use the searchable table to filter the reference data by the values, symbols, sizes, and applications that matter for your design check.
Quick check
Design check
Use the table for early sizing and drawing checks, then confirm final values against the governing standard.
Reference table
Imperial bolt size chart
| Thread Size | Major Diameter (in) | Minor Diameter (in) | Threads per Inch (TPI) | Pitch Diameter (in) | Tapping Drill Diameter (in) | Clearance Hole Diameter (in) |
|---|---|---|---|---|---|---|
| #0-80 | 0.060 | 0.049 | 80 | 0.054 | 0.046 | 0.073 |
| #2-56 | 0.086 | 0.073 | 56 | 0.079 | 0.073 | 0.106 |
| #4-40 | 0.112 | 0.098 | 40 | 0.105 | 0.099 | 0.138 |
| #6-32 | 0.138 | 0.120 | 32 | 0.127 | 0.120 | 0.164 |
| #8-32 | 0.164 | 0.140 | 32 | 0.152 | 0.139 | 0.190 |
| #10-24 | 0.190 | 0.164 | 24 | 0.172 | 0.166 | 0.216 |
| 1/4-20 | 0.250 | 0.215 | 20 | 0.225 | 0.201 | 0.281 |
| 5/16-18 | 0.3125 | 0.270 | 18 | 0.292 | 0.266 | 0.344 |
| 3/8-16 | 0.375 | 0.313 | 16 | 0.344 | 0.312 | 0.406 |
| 1/2-13 | 0.500 | 0.438 | 13 | 0.469 | 0.453 | 0.563 |
| 5/8-11 | 0.625 | 0.562 | 11 | 0.594 | 0.578 | 0.688 |
| 3/4-10 | 0.750 | 0.688 | 10 | 0.719 | 0.703 | 0.844 |
| 7/8-9 | 0.875 | 0.813 | 9 | 0.844 | 0.828 | 1.000 |
| 1-8 | 1.000 | 0.938 | 8 | 0.969 | 0.953 | 1.125 |
How to use
Practical checks for imperial bolt dimensions
Unit conversion
mm = in × 25.4
Use this for inch-to-metric conversions where the page includes dimensional data.
Clearance check
clearance = hole size - feature size
Positive clearance helps confirm whether a part can assemble freely.
Tolerance range
range = upper limit - lower limit
The usable manufacturing window is the difference between upper and lower limits.
Documentation check
value + unit + standard
Reference data is most useful when paired with units and the governing drawing or design standard.
Definitions
What the reference values mean
Reference Value
A tabulated value used for selection, comparison, or early design checks.
Nominal Size
The named or target size before manufacturing tolerance is applied.
Tolerance
The allowed variation from the nominal or specified value.
Standard
The source convention or governing document that defines how a value should be interpreted.
FAQ
Imperial Bolt Dimensions questions
How should I use this table?
Use it for quick comparison, preliminary design, drawing review, and shop reference.
Can this page replace the governing standard?
No. Use this page as a fast reference; final design and inspection should follow the current standard, drawing notes, and project requirements.
Why is the table searchable?
Search helps you jump directly to a size, symbol, process, value, or application without scanning every row.
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ISO shaft tolerance and fit reference.
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ISO keyway dimensions for shafts and hubs.
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Surface roughness values for machining and finishing processes.
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Common weld symbols and drawing reference.